Song from musical in East London (3)
I believe the answer is:
air
'song' is the definition.
(air can mean a piece of music)
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for air that I've seen before include "what emerges from singer's lungs?" , "Tune or aura" , "Refrain" , "Musical composition" , "A tune or attitude" .)