Fashionable princess in a state? (7)
I believe the answer is:
indiana
'state?' is the definition.
(US state)
'fashionable princess' is the wordplay.
'fashionable' becomes 'in' (in can mean fashionable or trendy).
'princess' becomes 'diana' (I have seen 'British princess' mean 'diana' so perhaps 'princess' could also mean 'diana').
'in'+'diana'='INDIANA'
'in a' is the link.
(Other definitions for indiana that I've seen before include "state of America" , "-- Jones, Harrison Ford role" , "Vice President Pence's state" , "Character associated with the Temple of Doom" , "The Hoosier State" .)