Books troublesome rugby players (9)

I believe the answer is:

hardbacks

'books' is the definition.
(hardback is a kind of book)

'troublesome rugby players' is the wordplay.
'troublesome' becomes 'hard' (similar in meaning).
'rugby players' becomes 'backs' (back is a type of rugby player).
'hard'+'backs'='HARDBACKS'

I've seen this clue in The Independent.

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