Perhaps a lofty Haydn piece? (3)
I believe the answer is:
hay
'piece?' is the definition.
The answer and definition can be both things that one consumes for nourishment as well as being singular nouns.
Maybe you can see a link between them that I can't see?
I don't understand the remainder of the clue.
Can you help me to learn more?
(Other definitions for hay that I've seen before include "Make . . . while the sun shines" , "Meadow crop" , "Animal fodder" , "It is to be made while the sun shines" , "Welsh festival" .)