Cork has to plug bottles (4)
I believe the answer is:
stop
'cork' is the definition.
(thesaurus)
'has to plug bottles' is the wordplay.
'bottles' indicates a hidden word (bottling is a kind of containing).
'STOP' is hidden in the letters of 'has to plug'.
(Other definitions for stop that I've seen before include "End - period" , "Withhold payment" , "Plug - organ knob - bus halt - period" , "Close < finish" , "Cease; organ voice" .)