The sound of music? (4)
I believe this clue is a double definition.
'the sound' is the first definition.
(pop is a kind of sound)
'music' is the second definition.
(pop music)
'of' is the link.
(Other definitions for pop that I've seen before include "Music with mass appeal" , "Old jingle - . . . goes the weasel" , "Palindrome of music for the young" , "Explode; Eton society" , "Explosive sound; drink" .)
(Other definitions for tune that I've seen before include "Optimise the condition of" , "Air, melody" , "Song" , "Melody; adjust (engine)" , "temper" .)
'the sound of music?' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for tone that I've seen before include "Musical sound; quality of hue" , "Quality or character of voice" , "Note; note (anag.)" , "Quality of sound, etc" , "Pitch (sound)" .)
(Other definitions for getz that I've seen before include "Stan -, American jazz saxophonist" , "Stan -, twentieth century US jazz saxophonist" .)