In appearance, possibly, it may be torn (5)

I believe the answer is:

paper

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'in' is the definition.
The definition and answer can be both substances as well as being singular nouns.
Perhaps they are linked in a way I don't understand?

I don't understand the rest of the clue.

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(Other definitions for paper that I've seen before include "conference presentation" , "Dissertation" , "Scholarly article" , "News medium" , "Set of written exam questions" .)

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