"Give it a rest!" (4)
I believe the answer is:
stop
'give it a rest' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for stop that I've seen before include "Plug - organ knob - bus halt - period" , "port of call" , "Withhold payment" , "Post (anag.)" , "Prevent - desist" .)