Clergyman's robe (7)
I believe the answer is:
cassock
'clergyman's robe' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for cassock that I've seen before include "Cossack (anag.)" , "Long garment worn by some clergy" , "Clergyman's robe" , "Ankle-length garment worn by priests and choristers" , "Long clerical robe" .)