Mistreated like a rent book (4)

I believe the answer is:

torn

I'm a little stuck... Click here to teach me more about this clue!

'rent book' is the definition.
'torn' can be an answer for 'rent' (I've seen this in another clue). I am not certain of the 'book' bit.

I cannot understand how the rest of the clue works.

Can you help me to learn more?

(Other definitions for torn that I've seen before include "Divided" , "Having rips" , "Lacerated - in two minds" , "Rent, ripped" , "Ragged" .)

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