Band upset priest (6)
I believe the answer is:
stripe
'band' is the definition.
(I know that band can be written as stripe)
'upset priest' is the wordplay.
'upset' indicates anagramming the letters.
'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" .)