Opera set in ancient Egypt (4)
I believe the answer is:
aida
'opera set in ancient egypt' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for aida that I've seen before include "Egyptian opera by 11 Down" , "She dies with Radams (Verdi)" , "Operatic lady" , "eponymous heroine" , "Verdi's opera set in ancient Egypt" .)