Jazz composer premieres in Manhattan - one nods knowingly (4)
I believe the answer is:
monk
'jazz composer' is the definition.
The answer and definition can be both people as well as being singular nouns.
Maybe there's a link between them I don't understand?
I don't understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for monk that I've seen before include "Setter" , "Male member of religious order" , "Thelonious - - (jazz)" , "Man in a religious order" , "prayer?" .)