Fighting, groom with a temperature (6)
I believe the answer is:
combat
'fighting' is the definition.
('combat' can be a synonym of 'fighting')
'groom with a temperature' is the wordplay.
'groom' becomes 'comb' (combing is a kind of grooming**).
'with' is a charade indicator (letters next to each other).
'temperature' becomes 't' (abbreviation).
'comb'+'a'+'t'='COMBAT'
(Other definitions for combat that I've seen before include "Armed fighting" , "War; contest" , "Fight, struggle or contest" , "A fight or contest, sometimes mortal" , "Battle or fight" .)