Film star Greta almost in dress (4)
I believe the answer is:
garb
'dress' is the definition.
(synonyms)
'film star greta almost' is the wordplay.
'film star greta' becomes 'Garbo' (Greta Garbo, 1905-1990).
'almost' means to remove the last letter (most of the word but not all of it).
'garbo' with its last letter taken away is 'GARB'.
'in' acts as a link.
(Other definitions for garb that I've seen before include "Outfit" , "Attire, clothing" , "Fashion of dress" , "Dress - habit" , "Distinctive dress of a group" .)