Priest upset by elf (6)
I believe the answer is:
sprite
'elf' is the definition.
(I've seen this before)
'priest upset' is the wordplay.
'upset' indicates anagramming the letters.
'priest' anagrammed gives 'SPRITE'.
'by' is the link.
(Other definitions for sprite that I've seen before include "Puck, say" , "Stripe on a fairy" , "A fairy or goblin" , "Impish type" , "Nimble elf-like creature - icon in computer game" .)