Turn and leave (2,3)
I believe the answer is:
go off
This clue is a double definition.
'turn' is the first definition.
(I've seen this before)
'leave' is the second definition.
(thesaurus)
'and' acts as a link.
(Other definitions for go off that I've seen before include "Rot; leave" , "Explode" , "Decay - become disenchanted with" , "Turn" , "fall asleep" .)