Some insolent note (3)
I believe the answer is:
sol
'note' is the definition.
(musical note as in do-re-mi-fa-sol-la-ti)
'some insolent' is the wordplay.
'some' indicates the answer is hidden within the clue (some of the parts of the word are used).
'SOL' is hidden within 'insolent'.
(Other definitions for sol that I've seen before include "Fifth note of scale" , "Note; Peruvian currency" , "Spanish and poetic sun" , "Mexican lager" , "Peruvian currency; Roman sun god" .)