Song Frau von Trapp won't start (4)
I believe the answer is:
aria
'song' is the definition.
(aria is a kind of song)
I don't understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for aria that I've seen before include "Nessun Dorma, for example" , "Puccini item" , "Imitative art work" , "Operatic air" , "part of opera, maybe" .)