Mother of Harry and William (5)
I believe the answer is:
diana
'mother of harry and william' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for diana that I've seen before include "Roman equivalent of Artemis" , "Girl's name; goddess" , "MONKEY" , "Roman godess of the hunt" , "Roman huntress goddess" .)