Ghoul, monster (5)
I believe the answer is:
fiend
This clue is a double definition.
'ghoul' is the first definition.
(thesaurus)
'monster' is the second definition.
(I know that monster can be written as fiend)
(Other definitions for fiend that I've seen before include "Demon, ogre" , "Evil supernatural being" , "Operatic super-soprano" , "addict" , "Devil" .)