Great book, in my opinion (4)

I believe the answer is:

tome

This clue is a double definition.

'great book' is the first definition.
(a tome is a large book)

'in my opinion' is the second definition.
(to me)

(Other definitions for tome that I've seen before include "Large heavy book" , "dictionary?" , "Large and scholarly book" , "Heavy volume" , "Big book" .)

I've seen this clue in The Guardian.

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