Idiosyncrasy regularly detected in fraud (3)

I believe the answer is:

fad

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'idiosyncrasy' is the definition.
(I've seen this before)

I don't understand the rest of the clue.

(Other definitions for fad that I've seen before include "A passing fashion or craze" , "Particular like or dislike, or a craze" , "Passing vogue or fashion" , "'Craze, all the rage (3)'" , "Craze; idiosyncrasy" .)

I've seen this clue in The Sun.

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