A song from Maria Callas? (4)
I believe the answer is:
aria
'a song' is the definition.
(I know that aria is a type of song)
'from maria callas?' is the wordplay.
'from' indicates a hidden word.
'ARIA' can be found hidden inside 'maria callas'.
(Other definitions for aria that I've seen before include "Operatic tune" , "Type of song" , "Operatic vocal" , "Repeated strain" , "Song such as "Your Tiny Hand is Frozen"" .)