Broadcasting revolutionary extract of Hungarian opera (2,3)
I believe the answer is:
on air
'broadcasting' is the definition.
(broadcasting on the air)
'revolutionary extract of hungarian opera' is the wordplay.
'revolutionary' is a reversal indicator.
'extract of' indicates a hidden word (I've seen this in other clues).
'riano' is hidden in the letters of 'hungarian opera'.
'riano' written backwards gives 'ON AIR'.
(Other definitions for on air that I've seen before include "In the process of broadcasting on radio or TV" , "(Walking) elatedly" , "If you're really happy, you'll float here" , "How one walks when elated" , "Walk in delight here" .)