Anger about fellow getting sack (5)
I believe the answer is:
rifle
'sack' is the definition.
(thesaurus)
'anger about fellow' is the wordplay.
'anger' becomes 'rile' (I've seen this in other clues).
'about' indicates putting letters inside.
'fellow' becomes 'f' (abbreviation - of a society etc.).
'rile' placed around 'f' is 'RIFLE'.
'getting' acts as a link.
(Other definitions for rifle that I've seen before include "Plunder - ransack" , "Flier (anag.)" , "Gun - steal" , "Gun; sack" , "Steal and carry off - firearm" .)