A couple of pages back to back (4)

I believe the answer is:

leaf

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'back' is the definition.
(thesaurus)

I cannot understand how the remainder of the clue works.

(Other definitions for leaf that I've seen before include "Growth on plant" , "Page of a book" , "Piece of foliage (to be turned over anew?)" , "Small part of wood" , "Page or piece of foliage" .)

I've seen this clue in the Evening Standard.

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