Actress Gwyn (4)
I believe the answer is:
nell
'actress gwyn' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for nell that I've seen before include "-- Gwyn, mistress of Charles II" , "Orphan girl" , "-- Gwyn, royal favourite" , "Dickensian heroine" , "First name of Charles II's ex-actress mistress" .)