Garment worn as penance (4,5)
I believe the answer is:
hair shirt
(Other definitions for hair shirt that I've seen before include "Penitential hirsute garment for upper part of man's body" , "A penitential garment of hirsute beginnings" , "Penitent's garb" , "Coarse hirsute garment worn over skin as a penance" , "article for an ascetic" .)