At full throttle (3-3)
I believe the answer is:
all-out
'at full throttle' is the definition.
(thesaurus)
This is the entire clue.
(Other definitions for all-out that I've seen before include "Thorough-going" , "At full speed - no one at home" , "Exerting maximum effort - nobody home" , "Using every resource" , "Using full strength or energy - nobody home?" .)