Duke ____ of jazz (9)
I believe the answer is:
ellington
'duke of jazz' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for ellington that I've seen before include "Musician" , "Duke (of jazz)" , "One Duke" , "Duke --, twentieth century band leader" , "Duke - (Mood Indigo)" .)