Anger about loud firearm (5)
I believe the answer is:
rifle
'firearm' is the definition.
(rifle is a kind of firearm)
'anger about loud' is the wordplay.
'anger' becomes 'rile' (I've seen this in another clue).
'about' indicates putting letters inside.
'loud' becomes 'f' (short for forte - 'loud' in music).
'rile' enclosing 'f' is 'RIFLE'.
(Other definitions for rifle that I've seen before include "Steal and carry off - firearm" , "Long-barrelled weapon, normal army equipment" , "Search and rob for army weapon" , "Go through in search" , "Firearm - plunder" .)