Last longer than unfashionable clothing (7)
I believe the answer is:
outwear
'last longer than' is the definition.
(I've seen this before)
'unfashionable clothing' is the wordplay.
'unfashionable' becomes 'out' ('out' can be a synonym of 'unfashionable').
'clothing' becomes 'wear' ('wear' can be a synonym of 'clothing'**).
'out'+'wear'='OUTWEAR'
(Other definitions for outwear that I've seen before include "ride" , "Last longer than others" , "may last longer" , "Top dressing" , "Drain" .)