"Orfeo" composer (10)
I believe the answer is:
monteverdi
'orfeo composer' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for monteverdi that I've seen before include "Claudio -, an early composer of operas" , "C Sixteen-Seventeen Italian composer (Orfeo)" , "Italian scorer" , "Claudio --, 16th-17th century Italian composer" , "Composer of "Orpheus"" .)