Having trouble with last 3
13d "Roll up to study very old instrument" (9) 
C?N?O?U?A  -  presumably name of an old musical instrument but can't see it 
19a "The way  to tackle long instrument" (6) 
S?I?E?  -  SPINET would be in keeping with theme but can't see the parsing 
10a "Group in the other marquee forget note" (6) 
?E?T?T   -   SEPTET would fit the theme but again can't parse
Any help greatly appreciated