There are such killers in fiction (6)

I believe the answer is:

serial

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'fiction' is the definition.
(I know that serial is a type of radio drama)

I cannot understand how the rest of the clue works.

Can you help me to learn more?

(Other definitions for serial that I've seen before include "Set of TV shows" , "TV drama in instalments" , "Story published in instalments" , "Continuous, perhaps like mulitple killer ( 6)" , "Episodic story from Israel" .)

I've seen this clue in the Evening Standard.

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