"Saints and Sinners” writer O'Brien (4)
I believe the answer is:
edna
(Other definitions for edna that I've seen before include "Barry Humphries' Dame" , "Prolific Irish woman novelist . . . . O'Brien" , "Girl's name; Dane (anag.)" , "- O'Brien, Ir. novelist" , ". . . . O'Brien, ... Saint Vincent Millay" .)