Department sacks Head of Chemistry for not working (6)

I believe the answer is:

faulty

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'for not working' is the definition.
(I've seen this before)

I don't understand the remainder of the clue.

(Other definitions for faulty that I've seen before include "Not working correctly" , "Defective, not in good working order" , "in error" , "Having a defect" , "Defective or inaccurate" .)

I've seen this clue in The Independent.

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