Priest's robe (3)
I believe the answer is:
alb
'priest's robe' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for alb that I've seen before include "the vicar might put on?" , "Devotional vestment" , "Long white robe worn by Christian priest" , "Cover" , "White clerical garment" .)