Hello,
I am building a flow that runs when a new MS Forms response is submitted.

I have added in the Get user profile (V2) action to grab the email address of the responder.
Then I use a Compose action to get the body of the above.

Next, I'm using this JSON this sample data in a "Parse JSON" action to separate the data from the output of the above.
Src: https://docs.microsoft.com/en-us/graph/api/resources/user?view=graph-rest-1.0#json-representation
{
"aboutMe": "String",
"accountEnabled": true,
"ageGroup": "String",
"assignedLicenses": [{"@odata.type": "microsoft.graph.assignedLicense"}],
"assignedPlans": [{"@odata.type": "microsoft.graph.assignedPlan"}],
"birthday": "String (timestamp)",
"businessPhones": ["String"],
"city": "String",
"companyName": "String",
"consentProvidedForMinor": "String",
"country": "String",
"createdDateTime": "String (timestamp)",
"creationType": "String",
"department": "String",
"displayName": "String",
"employeeHireDate": "2020-01-01T00:00:00Z",
"employeeId": "String",
"employeeOrgData": {"@odata.type": "microsoft.graph.employeeOrgData"},
"employeeType": "String",
"faxNumber" : "String",
"givenName": "String",
"hireDate": "String (timestamp)",
"id": "String (identifier)",
"identities": [{"@odata.type": "microsoft.graph.objectIdentity"}],
"imAddresses": ["String"],
"interests": ["String"],
"isResourceAccount": false,
"jobTitle": "String",
"legalAgeGroupClassification": "String",
"licenseAssignmentStates": [{"@odata.type": "microsoft.graph.licenseAssignmentState"}],
"lastPasswordChangeDateTime": "String (timestamp)",
"mail": "String",
"mailboxSettings": {"@odata.type": "microsoft.graph.mailboxSettings"},
"mailNickname": "String",
"mobilePhone": "String",
"mySite": "String",
"officeLocation": "String",
"onPremisesDistinguishedName": "String",
"onPremisesDomainName": "String",
"onPremisesExtensionAttributes": {"@odata.type": "microsoft.graph.onPremisesExtensionAttributes"},
"onPremisesImmutableId": "String",
"onPremisesLastSyncDateTime": "String (timestamp)",
"onPremisesProvisioningErrors": [{"@odata.type": "microsoft.graph.onPremisesProvisioningError"}],
"onPremisesSamAccountName": "String",
"onPremisesSecurityIdentifier": "String",
"onPremisesSyncEnabled": true,
"onPremisesUserPrincipalName": "String",
"otherMails": ["String"],
"passwordPolicies": "String",
"passwordProfile": {"@odata.type": "microsoft.graph.passwordProfile"},
"pastProjects": ["String"],
"postalCode": "String",
"preferredDataLocation": "String",
"preferredLanguage": "String",
"preferredName": "String",
"provisionedPlans": [{"@odata.type": "microsoft.graph.provisionedPlan"}],
"proxyAddresses": ["String"],
"responsibilities": ["String"],
"schools": ["String"],
"showInAddressList": true,
"signInSessionsValidFromDateTime": "String (timestamp)",
"skills": ["String"],
"state": "String",
"streetAddress": "String",
"surname": "String",
"usageLocation": "String",
"userPrincipalName": "String",
"userType": "String",
"calendar": { "@odata.type": "microsoft.graph.calendar" },
"calendarGroups": [{ "@odata.type": "microsoft.graph.calendarGroup" }],
"calendarView": [{ "@odata.type": "microsoft.graph.event" }],
"calendars": [ {"@odata.type": "microsoft.graph.calendar"} ],
"contacts": [ { "@odata.type": "microsoft.graph.contact" } ],
"contactFolders": [ { "@odata.type": "microsoft.graph.contactFolder" } ],
"createdObjects": [ { "@odata.type": "microsoft.graph.directoryObject" } ],
"directReports": [ { "@odata.type": "microsoft.graph.directoryObject" } ],
"drive": { "@odata.type": "microsoft.graph.drive" },
"drives": [ { "@odata.type": "microsoft.graph.drive" } ],
"events": [ { "@odata.type": "microsoft.graph.event" } ],
"inferenceClassification": { "@odata.type": "microsoft.graph.inferenceClassification" },
"mailFolders": [ { "@odata.type": "microsoft.graph.mailFolder" } ],
"manager": { "@odata.type": "microsoft.graph.directoryObject" },
"memberOf": [ { "@odata.type": "microsoft.graph.directoryObject" } ],
"messages": [ { "@odata.type": "microsoft.graph.message" } ],
"outlook": { "@odata.type": "microsoft.graph.outlookUser" },
"ownedDevices": [ { "@odata.type": "microsoft.graph.directoryObject" } ],
"ownedObjects": [ { "@odata.type": "microsoft.graph.directoryObject" } ],
"photo": { "@odata.type": "microsoft.graph.profilePhoto" },
"registeredDevices": [ { "@odata.type": "microsoft.graph.directoryObject" } ]
}

I am now using a SharePoint Create item action to fill the required fields with data from the parsed JSON.

When this flow run, it fails on the "Create item" step under the "Directorate" column where I have the onPremisesExtensionAttributes value inserted.
This seems to be because the onPremisesExtensionAttributes item has multiple values.

What I need to do is extract the value of extensionAttribute3 and populate this into the "Directorate" column in SharePoint.
(*obviously if I was using a multi-line text column, the flow would probably complete however I dont want all the data from onPremisesExtensionAttributes just extensionAttribute3.)
Any ideas?