Book a tough-tackling defender! (8)

I believe the answer is:

hardback

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'book' is the definition.
(I know that hardback is a type of book)

'a tough-tackling defender' is the wordplay.
'a tough' becomes 'hard' (I've seen this before).
'tackling defender' becomes 'back' (I am not sure about this - if you are sure you should believe this answer much more).
'hard'+'back'='HARDBACK'

Can you help me to learn more?

(Other definitions for hardback that I've seen before include "Style of book binding" , "It might be a novel!" , "Sort of book" , "Book with stiff covers" , "Durable version of book" .)

I've seen this clue in the Evening Standard.

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