Note ultimately made after upsetting part of speech (5)
I believe the answer is:
breve
'note' is the definition.
(musical note)
'ultimately made after upsetting part of speech' is the wordplay.
'ultimately' suggests the final letters.
'after' means one lot of letters go next to another.
'upsetting' says the letters should be written backwards.
'part of speech' becomes 'verb' (verb is a kind of part of speech).
The final letter of 'made' is 'e'.
'verb' back-to-front is 'brev'.
'e' after 'brev' is 'BREVE'.
(Other definitions for breve that I've seen before include "Accent placed over a vowel" , "Accent - musical note" , "Long note (mus.)" , "Rarely used musical note" , "(In music) long note" .)