"Rigoletto" highlight (4)
I believe the answer is:
aria
'rigoletto highlight' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for aria that I've seen before include "Imitative art work" , "Vocal solo in a cantata etc" , "selection of opera" , "Song from an opera (4)" , "Operatic song" .)