Perhaps Emperor Nero finally supporting unity (8)
I believe the answer is:
concerto
'perhaps emperor' is the definition.
I can't tell whether this definition defines the answer.
'nero finally supporting unity' is the wordplay.
'finally' says to take the final letters.
'supporting' says to put letters next to each other (in a down clue, some letters go below others).
'unity' becomes 'concert' (I can't justify this - if you can you should give a lot more credence to this answer).
The final letter of 'nero' is 'o'.
'o' after 'concert' is 'CONCERTO'.
Can you help me to learn more?
(Other definitions for concerto that I've seen before include "Musical piece for soloist(s) and orchestra" , "Composition for orchestra and soloist" , "Work for soloist and orchestra" , "Orchestral piece" , "Work for orchestra and soloist(s)" .)