Prepare to shoot: goal! (3)
I believe the answer is:
aim
I believe this clue is a double definition.
'prepare to shoot' is the first definition.
(as in aiming a gun)
'goal' is the second definition.
(aim is a kind of goal)
(Other definitions for aim that I've seen before include "Draw a bead on" , "Purpose in directing the rifle" , "Point or direct, a weapon say" , "Train" , "Purpose, intention" .)