Sack fellow in anger (5)
I believe the answer is:
rifle
'sack' is the definition.
(I've seen this before)
'fellow in anger' is the wordplay.
'fellow' becomes 'f' (abbreviation - of a society etc.).
'in' indicates putting letters inside.
'anger' becomes 'rile' (I've seen this in other clues).
'f' placed within 'rile' is 'RIFLE'.
(Other definitions for rifle that I've seen before include "Gun; sack" , "Firearm - plunder" , "disarray" , "Gun with a long barrel" , "An arm" .)