Note something not intended by a learner (10)
I believe the answer is:
accidental
'note' is the definition.
(I've seen this before)
'not intended by a learner' is the wordplay.
'not intended' becomes 'accident' (I am not sure about this - if you are sure you should believe this answer much more).
'by' is a charade indicator (letters next to each other).
'learner' becomes 'l' (as in a learner driver with L-plates on their car).
'accident'+'a'+'l'='ACCIDENTAL'
'something' acts as a link.
I am not very happy about this link. It may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for accidental that I've seen before include "Unintentional" , "Happening by chance" , "indication to modify tone slightly" , "Possible sharp" , "Sign raising or lowering a musical note" .)