Negative on notes, but actually quite good (3,3)
I believe the answer is:
not bad
'quite good' is the definition.
(I've seen this before)
'negative on notes but actually' is the wordplay.
I cannot really understand how this works, but
'negative' could be 'not' (I've seen this in another clue) and 'not' is located in the answer.
'notes' could be 'ba' and 'ba' is present 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 not bad that I've seen before include "Grudging praise" , "Informally good, a bit grudging" , "fine" , "Reasonably good in negative way" , "Negative sort of praise, fairly good" .)