Queen of Mount Olympus (4)
I believe the answer is:
hera
'queen of mount olympus' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for hera that I've seen before include "Greek goddess" , "Sister and wife of 18" , "Greek queen of Olympian gods" , "Divine consort" , "Zeus's wife and sister" .)