Organ score set aside (7)
I believe the answer is:
earmark
'set aside' is the definition.
(synonyms)
'organ score' is the wordplay.
'organ' becomes 'ear' (ear is a kind of organ).
'score' becomes 'mark' (synonyms).
'ear'+'mark'='EARMARK'
(Other definitions for earmark that I've seen before include "Set aside for a specific purpose" , "Set aside for special purpose" , "reserve for future use" , "spot where The Ring may be put on?" , "Set aside specifically" .)