Piece churchman and partner rejected (8)
I believe the answer is:
revolver
'piece' is the definition.
(revolver is a kind of piece)
'churchman and partner rejected' is the wordplay.
'churchman' becomes 'rev' (abbreviation for Reverend).
'and' means one lot of letters go next to another.
'partner' becomes 'lover' (I've seen this before).
'rejected' shows that the letters should be reversed in order.
'rev'+'lover'='revlover'
'revlover' written backwards gives 'REVOLVER'.
(Other definitions for revolver that I've seen before include "One goes round" , "firearm" , "Hand gun" , "murder weapon" , "needed for a roulette game?" .)