One note produces anger (3)
I believe the answer is:
ire
'anger' is the definition.
(ire is intense rage)
'one note' is the wordplay.
I cannot really understand how this works, but
'one' could be 'i' (Roman numeral) and 'i' is found in the answer.
'note' could be 're' (as in do-re-mi) and 're' is present in the answer.
This accounts for all the letters.
This may be the basis of clue (or it may be nonsense).
'produces' is the link.
Can you help me to learn more?
(Other definitions for ire that I've seen before include "passionate feeling" , "Anger, annoyance" , "Choler" , "Fury" , "'Anger, wrath (3)'" .)