Unfortunately ISE doesn't retrieve this attribute for an AD object - but you can tell ISE to do so, as follows. And I am no AD expert, but I think what you're looking for might be found in the userPrincipalName - e.g. in my lab my UPN is netadmin-ab@nrlab.local - the AD domain is rnlab.local - there are other attributes such as the distiniguishedName which also contains the AD in another format - e.g. DC=rnlab,DC=local
The method below will import the AD Attribute Name into ISE, so you can use it in your Policy Sets. You can give ISE an example username so that it can present a list for you - then you select the attributes you want:

Click OK and then Save.
You will then see this attribute in the Policy Set

Maybe this would suffice then:
