Priestly robes (4)
I believe the answer is:
albs
'priestly robes' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for albs that I've seen before include "White linen liturgical vestments" , "White liturgical vestment" , "Long white robes worn by priests" , "Slab (anag.)" .)