A sunny note (3)

I believe the answer is:

sol

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'note' is the definition.
(I know that sol is a type of note)

I don't understand how the rest of the clue works.

(Other definitions for sol that I've seen before include "Roman sun-god" , "The Sun (or Campbell?)" , "Personification of the sun" , "Musical note" , "Fifth note of scale" .)

I've seen this clue in the Evening Standard.

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