Suggestions of how to clue 'notes' (9)
I believe the answer is:
overtones
'suggestions' is the definition.
(I've seen this in another clue)
'of how to clue notes' is the wordplay.
I cannot quite understand how this works, but
'of' could be 'o' and 'o' is found in the answer.
'to' is found in the answer.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for overtones that I've seen before include "subtle innuendoes" , "added nuances" , "Subtle implications" , "Upper partials" .)