Revolutionary extract from Wagnerian opera being broadcast (2,3)
I believe the answer is:
on air
'being broadcast' is the definition.
(I've seen this before)
'revolutionary extract from wagnerian opera' is the wordplay.
'revolutionary' shows that the letters should be reversed in order.
'extract from' says the answer is hidden in the clue (I've seen this in other clues).
'riano' is hidden within 'wagnerian opera'.
'riano' written backwards gives 'ON AIR'.
(Other definitions for on air that I've seen before include "Currently broadcasting" , "now showing" , "In the process of broadcasting on radio or TV" , "Cushioned" , "put out" .)