Civilian clothes (5)
I believe the answer is:
mufti
'civilian clothes' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for mufti that I've seen before include "Civilian dress, worn by an off-duty soldier, say" , "Non-military clothing" , "Civvy dress" , "Soldier's civilian clothes" , "Muslim religious jurist" .)