Weighty book for my attention? (4)

I believe the answer is:

tome

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'weighty book' is the definition.
(I've seen this before)

I don't understand how the remainder of the clue works.

(Other definitions for tome that I've seen before include "Big book" , "Heavy volume" , "War and Peace, say" , "Hefty volume" , "Large, weighty book" .)

I've seen this clue in The Telegraph.

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