A city fashionable in the past (7)
I believe the answer is:
chicago
'a city' is the definition.
(Chicago is an example)
'fashionable in the past' is the wordplay.
'fashionable' becomes 'chic' (I've seen this before).
'in the past' becomes 'ago' ('ago' can be a synonym of 'in the past').
'chic'+'ago'='CHICAGO'
(Other definitions for chicago that I've seen before include "Type of bridge" , "A windy place" , "US city - musical featuring All That Jazz" , "Windy City of USA" , "City on Lake Michigan" .)