Fabulously long-eared monarch (5)
I believe the answer is:
midas
'monarch' is the definition.
(mythical king)
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for midas that I've seen before include "Golden-touch king" , "Gold-making king" , "old king" , "Gold-creating king" , "One with a golden touch" .)