Duff note held by trumpet (6)
I believe the answer is:
bungle
'duff' is the definition.
(duff can mean to bungle a golf shot)
'note held by trumpet' is the wordplay.
I cannot really understand how this works, but
'note' could be 'n' (abbreviation) and 'n' is found in the answer.
'trumpet' could be 'bugle' (I have seen 'Military trumpet ' mean 'bugle' so perhaps 'trumpet' could also mean 'bugle') and 'bugle' is located in the leftover letters.
No letters remain.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for bungle that I've seen before include "Make a hash of the job" , "Clumsy mistake" , "Tackle clumsily and fail" , "Badly handle" , "(Make an) embarrassing mistake" .)