Reject unfashionable shed (7)
I believe the answer is:
outcast
'reject' is the definition.
(thesaurus)
'unfashionable shed' is the wordplay.
'unfashionable' becomes 'out' ('out' can be a synonym of 'unfashionable').
'shed' becomes 'cast' (I've seen this before).
'out'+'cast'='OUTCAST'
(Other definitions for outcast that I've seen before include "Derelict" , "Pariah, leper" , "one sent to Coventry" , "He has been evicted from society" , "Role of Ishmael" .)