Monsters go back with resolution (5)
I believe the answer is:
ogres
'monsters' is the definition.
(ogre is a type of monster)
'go back with resolution' is the wordplay.
'back' says the letters should be written in reverse.
'with' means one lot of letters go next to another.
'resolution' becomes 'res' (I've seen this in other clues).
'go' in reverse letter order is 'og'.
'og'+'res'='OGRES'
(Other definitions for ogres that I've seen before include "Monstrous giants and man-eaters" , "Fairytale giants" , "Terrifying types" , "Gorse (anag.)" , "Formidable people" .)