Saint, mature, revealing band of colour (6)
I believe the answer is:
stripe
'band of colour' is the definition.
(I've seen this before)
'saint mature' is the wordplay.
'saint' becomes 'st' (abbreviation).
'mature' becomes 'ripe' (similar in meaning).
'st'+'ripe'='STRIPE'
'revealing' is the link.
(Other definitions for stripe that I've seen before include "Narrow band of colour" , "Braid showing military rank" , "Band of colour - 3 of rank" , "Sleeve badge showing military rank" , "Sign of a soldier's rank" .)