Study overlooking a Communist (3)
I believe the answer is:
red
'communist' is the definition.
(red can informally mean communist)
'study overlooking a' is the wordplay.
'study' becomes 'read' (synonyms).
'overlooking' indicates named letters should be taken away.
'read' with 'a' removed is 'RED'.
(Other definitions for red that I've seen before include "socialist?" , "Colour for danger" , "Carmine" , "Inflamed" , "Primary colour" .)