Stone work's finish (4)
I believe the answer is:
stop
'finish' is the definition.
('stop' can be a synonym of 'finish')
'stone work's' is the wordplay.
'stone' becomes 'st'.
'work' becomes 'op' (abbreviation for opus).
'st'+'op'='STOP'
(Other definitions for stop that I've seen before include "Discontinue (an action)" , "Stay" , "break" , "Come to a halt" , "oboe, perhaps" .)