Music found in magazine under newspaper (7)
I believe the answer is:
ragtime
'music' is the definition.
(ragtime is a kind of music)
'magazine under newspaper' is the wordplay.
'magazine' becomes 'time' (US magazine).
'under' means one lot of letters go next to another (below, in a down clue).
'newspaper' becomes 'rag' (informal term for a newspaper).
'time' put after 'rag' is 'RAGTIME'.
'found in' is the link.
(Other definitions for ragtime that I've seen before include "musical style" , "Kind of jazz for Maigret" , "Syncopated piano music from the 1890s" , "Maigret (anag)" , "Jazz music for Maigret" .)