Band upset priest (6)
I believe the answer is:
stripe
'band' is the definition.
('stripe' can be a synonym of 'band')
'upset priest' is the wordplay.
'upset' indicates an anagram.
'priest' with letters rearranged gives 'STRIPE'.
(Other definitions for stripe that I've seen before include "Band of colour - 3 of rank" , "Piece of braid indicating military rank" , "Band of contrasting colour" , "bar" , "Broad band" .)