Dud notes! (3)
I believe the answer is:
bad
'dud' is the definition.
Both the definition and answer are adjectives. Perhaps there's an association between them I don't understand?
'notes' is the wordplay.
I cannot really understand how this works, but
'notes' could be 'ba' and 'ba' is found in the answer.
A single letter 'd' remains which might be clued in a way I don't understand.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for bad that I've seen before include "Severe; of low standard" , "not healthy" , "Stinking" , "Ill" , "(Of food) decayed" .)