Heavy-hearted female character in opera (4)
I believe the answer is:
aida
'opera' is the definition.
(Verdi opera)
'heavy-hearted female character in' is the wordplay.
'heavy-hearted female' becomes 'ada' (woman's name. I am not sure about the 'heavy-hearted' bit.).
'character' becomes 'i'.
'in' means one lot of letters goes inside another.
'ada' going around 'i' is 'AIDA'.
Can you help me to learn more?
(Other definitions for aida that I've seen before include "slave of Covent Garden" , "Princess" , "Verdi's slave girl" , "title role" , "Fragrant shrub" .)