Cancel binding a yearbook (6)
I believe the answer is:
annual
'yearbook' is the definition.
(I know that yearbook can be written as annual)
'cancel binding a' is the wordplay.
'cancel' becomes 'annul' (annulling is a kind of cancelling).
'binding' indicates putting letters inside.
'annul' enclosing 'a' is 'ANNUAL'.
(Other definitions for annual that I've seen before include "Lasting for a year" , "Once a year, perhaps a book" , "Type of year book" , "Plant; yearbook" , "Book published yearly" .)