Tom turns on me for making a bungle (4-2)

I believe the answer is:

mess-up

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'a bungle' is the definition.
(I know that bungle can be written as mess up)

I cannot understand how the rest of the clue works.

Can you help me to learn more?

(Other definitions for mess-up that I've seen before include "Botch" , "Handle (something) ineptly" , "Muddle, bungle" , "Muddle - confusion" , "Fiasco" .)

I've seen this clue in the Evening Standard.

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