Old film star seen in dress circle (5)
I believe the answer is:
garbo
'old film star' is the definition.
(I know that Garbo was a movie star)
'dress circle' is the wordplay.
'dress' becomes 'garb' (synonyms).
'circle' becomes 'O' (O is a circle).
'garb'+'o'='GARBO'
'seen in' acts as a link.
(Other definitions for garbo that I've seen before include "Reclusive film star" , "Swedish actress born Greta Gustafsson" , "film star? Yes and no" , "Old film actress" , "Swedish actress who wanted to be alone" .)