A note turned into performance (6)
I believe the answer is:
action
'performance' is the definition.
(I've seen this in another clue)
'a note turned into' is the wordplay.
'note' becomes 'c' (musical note).
'turned' indicates an anagram.
'into' anagrammed gives 'tion'.
'a'+'c'+'tion'='ACTION'
(Other definitions for action that I've seen before include "Carry out" , "Law suit" , "Lawsuit; something done" , "Accomplishment" , "Director's call" .)