Scale note (3)
I believe the answer is:
sol
'scale note' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for sol that I've seen before include "Spanish and poetic sun" , "Roman counterpart of Helios" , "Peruvian currency; Roman sun god" , "nearby star" , "Note; Peruvian currency" .)