Success story? (4,6)

I believe the answer is:

best seller

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'success story?' is the definition.
The definition and answer can be both related to communication as well as being singular nouns.
Maybe there's an association between them I don't understand?

This is the entire clue.

Can you help me to learn more?

(Other definitions for best seller that I've seen before include "Popular book" , "Book bought in large numbers" , "Book bought by many" , "Blockbuster" , "What many people are buying" .)

I've seen this clue in The Globe and Mail.

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