Librettist's assignment (5)

I believe the answer is:
opera
(Other definitions for opera that I've seen before include "Musical works" , "Eg, Der Rosenkavalier" , "Patience, perhaps" , "Musical stage work" , "Musical extravaganza" .)
I believe the answer is:
opera
(Other definitions for opera that I've seen before include "Musical works" , "Eg, Der Rosenkavalier" , "Patience, perhaps" , "Musical stage work" , "Musical extravaganza" .)