Sky broadcast quality song (3)
I believe the answer is:
air
I believe this is a quadruple definition!!
'sky' is the first definition.
(I've seen this in another clue)
'broadcast' is the second definition.
(to air on TV)
'quality' is the third definition.
(air can mean a quality or character)
'song' is the fourth definition.
(air can mean a piece of music)
(Other definitions for air that I've seen before include "Light wind; song" , "Substance breathed in" , "in which birds fly around" , "Atmosphere (of a melody?)" , "Cause of inflation" .)