Combatants reeling dazedly, overwhelmed by blows (12)
I believe the answer is:
belligerents
'combatants' is the definition.
('belligerent' can be a synonym of 'combatant')
'reeling dazedly overwhelmed by blows' is the wordplay.
'dazedly' indicates anagramming the letters (the letters become confused or dazed).
'overwhelmed by' means one lot of letters goes inside another (I've seen this in other clues).
'blows' becomes 'belts' (both can mean to hit violently).
'reeling' anagrammed gives 'ligeren'.
'ligeren' put inside 'belts' is 'BELLIGERENTS'.
(Another definition for belligerents that I've seen is " Warmongers".)