Scrap broadcast about jazz (7)
I believe the answer is:
ragtime
'jazz' is the definition.
(type of jazz)
'scrap broadcast about' is the wordplay.
'scrap' becomes 'rag' (I've seen this in other clues).
'broadcast' becomes 'emit' (to emit is to broadcast or give out).
'about' says the letters should be written in reverse.
'emit' in reverse letter order is 'time'.
'rag'+'time'='RAGTIME'
(Other definitions for ragtime that I've seen before include "Kind of music" , "Scott Joplin genre" , "Scott Joplin art form" , "Syncopated music genre" , "Jazz music for Maigret" .)