Tool causing catastrophe in works? (7)

I believe the answer is:

spanner

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'tool' is the definition.
(spanner is a kind of tool)

I don't understand the rest of the clue.

(Other definitions for spanner that I've seen before include "Bolt tightener" , "Wrench for nuts" , "Hand tool for nuts" , "Hand tool to grip and turn" , "Mechanic's agent" .)

I've seen this clue in The Sun.

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