Place is monstrosity we hear (4)
I believe the answer is:
site
'place' is the definition.
(synonyms)
'monstrosity we hear' is the wordplay.
'monstrosity' becomes 'sight' (I've seen this before).
'we hear' shows a homophone (sound like).
'sight' is a homophone of 'SITE'.
'is' acts as a link.
(Other definitions for site that I've seen before include "Area set aside for building" , "Building land" , "Where something is located" , "Position; situation" , "internet location" .)