Fashionable girl in a state? (7)
I believe the answer is:
indiana
'state' is the definition.
(US state)
'fashionable girl' is the wordplay.
'fashionable' becomes 'in' (in can mean fashionable or trendy).
'girl' becomes 'diana' ().
'in'+'diana'='INDIANA'
'in a' acts as a link.
(Other definitions for indiana that I've seen before include "Midwestern state" , "Part of US" , "member of 2 [THE STATES]" , "state of America" , "State between Illinois/Ohio" .)