Shelves about right for account books (7)
I believe the answer is:
ledgers
'account books' is the definition.
('ledger' can be a synonym of 'account book')
'shelves about right for' is the wordplay.
'shelves' becomes 'ledges' ('ledge' can be a synonym of 'shelf').
'about' is an insertion indicator.
'right for' becomes 'r' (I can't explain this - if you can you should believe this answer much more).
'ledges' placed around 'r' is 'LEDGERS'.
Can you help me to learn more?
(Other definitions for ledgers that I've seen before include "Account-books" , "Account books" , "Books listing commercial transactions" , "Books of accounts" , "old spreadsheets" .)