Fellow man in conflict (4)
I believe the answer is:
fray
'conflict' is the definition.
(I know that fray is a type of combat)
'fellow man' is the wordplay.
'fellow' becomes 'f' (abbreviation - of a society etc.).
'man' becomes 'ray' (Man Ray was a 20th-century artist).
'f'+'ray'='FRAY'
'in' acts as a link.
(Other definitions for fray that I've seen before include "Chafe" , "Tempers may do" , "Noisy fight" , "Donnybrook, free-for-all" , "Suffer peripheral damage" .)