Combatant repressing rage left bar, starting ignition (11)
I believe the answer is:
firelighter
'bar starting ignition' is the definition.
(device used to start a fire)
'combatant repressing rage left' is the wordplay.
'combatant' becomes 'fighter' (synonyms).
'repressing' is an insertion indicator.
'rage' becomes 'ire' (I've seen this before).
'left' becomes 'l' (common abbreviation).
'ire'+'l'='irel'
'fighter' placed around 'irel' is 'FIRELIGHTER'.
(Other definitions for firelighter that I've seen before include "Flammable material" , "could produce a blaze" .)