Firing range purchase (4)
I believe the answer is:
ammo
'firing range purchase' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for ammo that I've seen before include "Bullets, shells (colloq.)" , "Projectiles" , "Bullets etc.(informal)" , "explosives, perhaps" , "eg Bullets, shells" .)