Priest converted imp (6)
I believe the answer is:
sprite
'imp' is the definition.
(I've seen this before)
'priest converted' is the wordplay.
'converted' indicates anagramming the letters.
'priest' anagrammed gives 'SPRITE'.
(Other definitions for sprite that I've seen before include "Impish type" , "water pixie" , "Supernatural being" , "Small, playful fairy" , "Brownie" .)