Moorehead of "Bewitched" (5)
I believe the answer is:
'moorehead of bewitched' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for agnes that I've seen before include "lass" , "Miss Grey" , "Tube for cables" , "David's second wife" , "St --' Eve, poem by Lord Tennyson" .)