Fought back, and sat on work (7)
I believe the answer is:
opposed
'fought back' is the definition.
('oppose' can be a synonym of 'fight back')
'sat on work' is the wordplay.
'sat' becomes 'posed' ('pose' can be a synonym of 'sit').
'on' is a charade indicator (letters next to each other).
'work' becomes 'op' (abbreviation for opus).
'posed' put after 'op' is 'OPPOSED'.
'and' is the link.
(Other definitions for opposed that I've seen before include "Competed with" , "Fought back" , "like foes" , "Confronted" , "Contested" .)