Minister finished scoffing large piece (8)
I believe the answer is:
revolver
'piece' is the definition.
(I know that revolver is a type of pistol)
'minister finished scoffing large' is the wordplay.
'minister' becomes 'rev' (short for reverend).
'finished' becomes 'over' (similar in meaning).
'scoffing' means one lot of letters goes inside another.
'large' becomes 'L' (eg in clothes sizes).
'over' placed around 'l' is 'olver'.
'rev'+'olver'='REVOLVER'
(Other definitions for revolver that I've seen before include "One goes round" , "murder weapon" , "Type of gun" , "Pistol - Beatles album" , "firearm" .)