Genre developed with last Handel opera (6,3,6)
I believe the answer is:
hansel and gretel
'opera' is the definition.
(I've seen this before)
'genre developed with last handel' is the wordplay.
'developed with' is an anagram indicator.
'last'+'handel'='lasthandel'
'genre' mixed up with 'lasthandel' gives 'HANSEL AND GRETEL'.
(Other definitions for hansel and gretel that I've seen before include "18 [OPERA]" , "fairy tale" , "Witch-killing pair" , "children abandoned in forest" , "Fairy story" .)