Broadcast melody (3)
I believe the answer is:
air
I believe this clue is a double definition.
'broadcast' is the first definition.
(I've seen this before)
'melody' is the second definition.
('air' can be a synonym of 'melody')
(Other definitions for air that I've seen before include "Broadcast; gas" , "Region above the ground" , "A melody or attitude" , "A number" , "Musical composition" .)