Convict fashionable couple (6)
I believe the answer is:
inmate
'convict' is the definition.
(I've seen this before)
'fashionable couple' is the wordplay.
'fashionable' becomes 'in' ('in' can be similar in meaning to 'fashionable').
'couple' becomes 'mate' ('mate' can be a synonym of 'couple'**).
'in'+'mate'='INMATE'
(Other definitions for inmate that I've seen before include "eg Prisoner" , "One institutionally confined" , "Inhabitant of prison or hospital" , "One is confined to an institution" , "Person serving a jail sentence" .)