Mounted clip gripping fashionable garment (5)
I believe the answer is:
tunic
'garment' is the definition.
(tunic is a kind of garment)
'mounted clip gripping fashionable' is the wordplay.
'mounted' is a reversal indicator.
'clip' becomes 'cut' (I've seen this before).
'gripping' indicates putting letters inside.
'fashionable' becomes 'in' ('in' can be similar in meaning to 'fashionable').
'cut' placed around 'in' is 'cinut'.
'cinut' in reverse letter order is 'TUNIC'.
(Other definitions for tunic that I've seen before include "Upper garment, for a soldier say" , "Close fitting jacket as part of uniform" , "Close-fitting jacket that's part of a uniform" , "Short uniform coat" , "Dress for soldier" .)