Mistakes in a book (6)
I believe the answer is:
errata
'mistakes in a book' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for errata that I've seen before include "(Printing) errors" , "mistakes in print" , "Mistakes in printed proofs" , "List of text corrections to be made in a publication" , "Noted mistakes" .)