Those remaining, cunning, begin again (7)
I believe the answer is:
restart
'begin again' is the definition.
('start' can be a synonym for 'begin' so perhaps 'restart' is OK for 'begin again')
'those remaining cunning' is the wordplay.
'those remaining' becomes 'rest'.
'cunning' becomes 'art' (I've seen this before).
'rest'+'art'='RESTART'
(Other definitions for restart that I've seen before include "launch again" , "Commence again" , "Begin anew" , "Jumping the gun will mean" , "begin afresh" .)