Front bit missing from toy weapon (5)
I believe the answer is:
rifle
'weapon' is the definition.
(rifle is a kind of weapon)
'front bit missing from toy' is the wordplay.
'front bit missing from' means to remove the first letter.
'toy' becomes 'trifle' (I've seen this before).
'trifle' with its initial letter taken off is 'RIFLE'.
(Other definitions for rifle that I've seen before include "Ransack - firearm" , "Winchester" , "One that has stock" , "Root" , "Lifer (anag.)" .)