Opera singer (4)
'opera singer' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for diva that I've seen before include "One who sings" , "Successful lady" , "For example Sutherland" , "Female opera star" , "Long narrow top" .)
(Other definitions for lulu that I've seen before include "Outstanding example of its kind - Alban Berg opera - Scottish pop singer, b. 1948" , "Exceptional thing (colloq.); Berg opera" , "Berg's unfinished opera" , "Attractive girl" , "beauty" .)
'opera singer' is the definition.
(thesaurus)
This is the entire clue.
(Other definitions for basso that I've seen before include "Lowest male singing voice (sometimes 'profundo')" , "low voice" , "Singer" , "one's deep in sound" .)