Broadcasting as one walking very happily? (2,3)
I believe the answer is:
on air
I believe this clue is a double definition.
'broadcasting' is the first definition.
(I've seen this before)
'as one walking very happily?' is the second definition.
(as in the phrase 'walking on air')
(Other definitions for on air that I've seen before include "In the process of broadcasting on radio or TV" , "very happily?" , "Transmitting now!" , "In the act of broadcasting" , "In the process of broadcasting - floating aloft?" .)