Cease work below street (4)
I believe the answer is:
stop
'cease' is the definition.
('stop' can be a synonym of 'cease')
'work below street' is the wordplay.
'work' becomes 'op' (abbreviation for opus).
'below' means one lot of letters go next to another.
'street' becomes 'st'.
'op' after 'st' is 'STOP'.
(Other definitions for stop that I've seen before include "Intercept" , "Don't allow" , "Hold on" , "Cease, desist, whoa" , "Stay" .)