Go to wound as Casca (4)
I believe the answer is:
stab
I believe this clue is a double definition.
'go' is the first definition.
(both can mean an attempt)
'wound as casca' is the second definition.
(I've seen this before)
'to' acts as a link.
(Other definitions for stab that I've seen before include "Wound with a dagger" , "pink" , "Pierce with something pointed" , "Attack with a dagger" , "shot in the dark?" .)