Princess in an opera, not a princess in an operetta (3)
I believe the answer is:
ida
'princess' is the definition.
(Princess Ida is a Gilbert and Sullivan opera)
'an opera not a princess in an operetta' is the wordplay.
I cannot quite see how this works, but
'an' could be 'i' (Roman numeral for one) and 'i' is present in the answer.
'a' is within the answer.
A single letter 'd' remains which might be clued in a way I don't understand.
This explanation may well be incorrect...
'in' is the link.
Can you help me to learn more?
(Other definitions for ida that I've seen before include "Poetic princess" , "noted princess" , "musical princess" , "Princess in a Gilbert and Sullivan comic opera" , "Princess __ (G&S comic opera)" .)