Do whatever it takes (4,2,7)
I believe the answer is:
stop at nothing
'do whatever it takes' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for stop at nothing that I've seen before include "Be totally ruthless" , "3 [COUNTDOWN CONUMDRUM] will" , "as announcers of rocket launches do?" , "Act ruthlessly" , "Ignore all scruples" .)