Misled Gerry about this book? (6)
I believe the answer is:
ledger
'this book?' is the definition.
(ledger is a kind of book)
'misled gerry about' is the wordplay.
'about' says the answer is hidden in the clue (the clue goes around or about the answer).
'LEDGER' can be found hidden inside 'misled gerry'.
(Other definitions for ledger that I've seen before include "Book for keeping financial accounts" , "Book-keeper's book" , "In which accounts are entered" , "Accounts journal" , "Old-fashioned heavy accounts book" .)