At start of book, one gets stuck (8)

I believe the answer is:

end paper

'at' is the definition.
Both the definition and answer are singular nouns.
Maybe they are linked in a way I don't understand?

I can't explain the remainder of the clue.

(Other definitions for end paper that I've seen before include "Leaf inside cover of book" , "First or last leaf in a book" .)

I've seen this clue in The Guardian.

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