Bouncy melody (4)
I believe the answer is:
lilt
'bouncy melody' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for lilt that I've seen before include "Cheerful tune" , "Tune with light pleasant rhythm" , "Jaunty musical rhythm" , "Cadence (in speech)" , "happy music" .)