Finish work on stone (4)
I believe the answer is:
stop
'finish' is the definition.
('stop' can be a synonym of 'finish')
'work on stone' is the wordplay.
'work' becomes 'op' (abbreviation for opus).
'on' is a charade indicator (letters next to each other).
'stone' becomes 'st'.
'op' after 'st' is 'STOP'.
(Other definitions for stop that I've seen before include "high card in bridge" , "Cease; organ voice" , "Prevent - desist" , "Go no further" , "Knock out" .)