Target I eliminated before second round? (4)
I believe the answer is:
ammo
'round?' is the definition.
(round is a kind of ammo)
'target i eliminated before second' is the wordplay.
'target' becomes 'aim' (both can mean a goal or purpose).
'eliminated' indicates named letters should be taken away.
'before' means one lot of letters go next to another.
'second' becomes 'mo' (both are short periods of time).
'aim' with 'i' taken away is 'am'.
'am'+'mo'='AMMO'
(Other definitions for ammo that I've seen before include "Projectiles" , "What's fired from guns (abbr)" , "that goes in magazine: ...?" , "explosives, perhaps" , "What's fired from a gun (abbr)" .)