Custom religious garment (5)
I believe the answer is:
habit
I believe this clue is a double definition.
'custom' is the first definition.
(I know that habit is a type of custom)
'religious garment' is the second definition.
(as in a nun's habit)
(Other definitions for habit that I've seen before include "Settled tendency" , "Custom or monk's robe" , "addictive practice" , "Propensity" , "Custom, wont" .)