A failure up to no good again (3)

I believe the answer is:

dud

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'a failure' is the definition.
(I know that dud is a type of failure)

I can't explain the remainder of the clue.

(Other definitions for dud that I've seen before include "Thing that fails to work" , "Useless, ineffective" , "A palindromic failure" , "Failing to work or meet standard (colloq.)" , "A palindromic washout" .)

I've seen this clue in the Evening Standard.

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