A lot of notes presented by old book (6)
I believe the answer is:
octavo
'book' is the definition.
(I know that octavo is a type of book)
'a lot of notes presented by old' is the wordplay.
'a lot of notes' becomes 'octav' (I can't justify this - if you can you should give a lot more credence to this answer).
'presented by' is a charade indicator (letters next to each other).
'old' becomes 'o' (common abbreviation eg in OE for Old English).
'octav'+'o'='OCTAVO'
Can you help me to learn more?
(Other definitions for octavo that I've seen before include "Size of a book, pages are made by folding a sheet of paper three times to form eight leaves (6)" , "Common book size" , "Size of book page" , "An eight-leaved book or page" .)