Monster: some macho greaser! (4)
I believe the answer is:
ogre
'monster' is the definition.
(fairy tale monster)
'some macho greaser' is the wordplay.
'some' says the answer is hidden in the clue (some of the parts of the word are used).
'OGRE' is hidden within 'macho greaser'.
(Other definitions for ogre that I've seen before include "terrible person" , "Cruel and wicked person" , "Giant who eats people" , "Terrifying person" , "One to gobble flesh" .)