Oberon's queen (7)
I believe the answer is:
titania
'oberon's queen' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for titania that I've seen before include "Queen of fairyland" , "asinine lover" , "in the D [DREAM] ..." , "Shakespeare's queen of the fairies" , "Fairy Queen (MND)" .)