Noted part-player on stage (5,6)
I believe the answer is:
opera singer
'stage' is the definition.
I know nothing about this answer so I cannot judge whether it can be defined by this definition.
'noted part-player on' is the wordplay.
'noted part' becomes 'opera' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'player' becomes 'singer' (singer is a kind of player).
'on' says to put letters next to each other.
'opera'+'singer'='OPERA-SINGER'
Can you help me to learn more?
(Other definitions for opera singer that I've seen before include "diva" , "Butt perhaps" , "Eg, Luciano Pavarotti" , "La Scala artiste" , "Prima donna" .)