The book on the shelf to the right (6)
I believe the answer is:
ledger
'the book' is the definition.
(ledger is a kind of book)
'on the shelf to the right' is the wordplay.
'on' is a charade indicator (letters next to each other).
'the shelf' becomes 'ledge' ('ledge' can be a synonym of 'shelf').
'to the right' becomes 'r' (common abbreviation).
'ledge' next to 'r' is 'LEDGER'.
(Other definitions for ledger that I've seen before include "Business record book" , "Old accounts book" , "Accounts journal" , "Old-fashioned heavy accounts book" , "Account book" .)