Actress Best (4)
I believe the answer is:
edna
'actress best' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for edna that I've seen before include ". . . . O'Brien, ... Saint Vincent Millay" , "- O'Brien, Irish writer" , "___ O'Brien, Irish novelist, b. 1930" , "Prolific Irish woman novelist . . . . O'Brien" , "Famous dame" .)