Kind of music popular with children? (5)
I believe the answer is:
'kind of music' is the definition.
'popular with children?' is the wordplay.
I cannot quite understand how this works, but
'popular' could be 'in' ('in' can mean trendy) and 'in' is located in the answer.
'with' could be 'w' (abbreviation) and 'w' is located in the answer.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for swing that I've seen before include "1930s' big band dance music - playground feature" , "throw a punch" , "Sweeping blow or stroke" , "coming and going" , "Jaunty rhythm in music" .)