Style of operatic singing, as that of Callas, say (3,5)
I believe the answer is:
bel canto
(Other definitions for bel canto that I've seen before include "Lyrical operatic style" , "Style of operatic singing, as that of Callas, say" , "Operatic singing style - noble act (anag)" , "Lyrical style of opera singing" , "Type of singing" .)