Melody, tune (3)
I believe the answer is:
air
I believe this is a double definition.
'melody' is the first definition.
(air can mean a tune or melody)
'tune' is the second definition.
(air can mean a piece of music)
(Other definitions for air that I've seen before include "'Tune, melody (3)'" , "Light breeze" , "Cool" , "Ventilate or give expression to" , "put on radio?" .)