Stop, terminate (5)
I believe the answer is:
cease
I believe this clue is a double definition.
'stop' is the first definition.
(synonyms)
'terminate' is the second definition.
(I know that terminate can be written as cease)
(Other definitions for cease that I've seen before include "Stop, finish" , "Come to an end" , "Stop, terminate" , "Finish, end" , "Stop, give over" .)