Note died away, but helped (5)
I believe the answer is:
aided
'helped' is the definition.
('aid' can be a synonym of 'help')
'note died away' is the wordplay.
'note' becomes 'a' (musical note).
'away' indicates anagramming the letters (letters move away from their original places).
'died' anagrammed gives 'ided'.
'a'+'ided'='AIDED'
'but' acts as a link.
(Other definitions for aided that I've seen before include "'Assisted, helped (5)'" , "not under their own steam?" , "given assistance" .)