Go flipping bonkers! (4)
I believe the answer is:
stab
'go' is the definition.
(both can mean an attempt)
'flipping bonkers' is the wordplay.
'flipping' is a reversal indicator.
'bonkers' becomes 'bats' ('bats' can be a synonym of 'bonkers').
'bats' written backwards gives 'STAB'.
(Other definitions for stab that I've seen before include "Strike with knife" , "wound as Casca" , "Try - skewer" , "effort" , "Sudden sharp feeling" .)