Jaunty tune (4)
I believe the answer is:
lilt
'jaunty tune' 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" , "Swing - music" , "Rise and fall" , "Pleasant gentle accent" , "Characteristic voice rhythm; Scots tune" .)