Note is almost exclusive (3)
I believe the answer is:
sol
'note' is the definition.
(musical note as in do-re-mi-fa-sol-la-ti)
'almost exclusive' is the wordplay.
'almost' means to remove the last letter (almost the whole word is kept).
'exclusive' becomes 'sole' (synonyms).
'sole' with its final letter taken off is 'SOL'.
'is' acts as a link.
(Other definitions for sol that I've seen before include "The sun in Spain" , "Mexican lager" , "Musical note" , "Spanish and poetic sun" , "nearby star" .)