Monsters making a lot of progress (5)
I believe the answer is:
ogres
'monsters' is the definition.
(ogre is a type of monster)
'a lot of progress' is the wordplay.
'a lot of' indicates a hidden word (I've seen 'a lot' mean this (a lot of the letters from the clue)).
'OGRES' is hidden within 'progress'.
'making' acts as a link.
(Other definitions for ogres that I've seen before include "Giant types" , "intimidating people" , "Terrifying types" , "She-giant of fairy tale" , "Man-eating giants of folklore" .)