Priests playing in bands (7)
I believe the answer is:
stripes
'bands' is the definition.
('stripe' can be a synonym of 'band')
'priests playing' is the wordplay.
'playing' indicates an anagram.
'priests' with letters rearranged gives 'STRIPES'.
'in' acts as a link.
(Other definitions for stripes that I've seen before include "Long narrow bands" , "As standard feature" , "Chevrons on uniforms" , "See 17" , "Persist (anag)" .)