Mob upset when a guy's out for a fight (6)
I believe the answer is:
combat
'a fight' is the definition.
('combat' can be a synonym of 'fight')
'mob upset when a guy's out' is the wordplay.
I cannot really understand how this works, but
an anagram of 'mob' is 'omb' which is located in the answer.
'a' is within the answer.
This explanation may well be incorrect...
'for' is the link.
Can you help me to learn more?
(Other definitions for combat that I've seen before include "Battle or fight" , "Armed fighting" , "Military action" , "Fight against; fighting" , "A fight or contest, sometimes mortal" .)