Go — attack! (4)
I believe the answer is:
stab
I believe this is a double definition.
'go' is the first definition.
(both can mean an attempt)
'attack' is the second definition.
(stab with a knife)
(Other definitions for stab that I've seen before include "Thrust at and pierce" , "Puncture" , "It could be the death of you" , "Attack with a dagger" , "Sudden sharp feeling" .)