Amateur chef wearing a white cooking apron is about to chop a chicken with a butcher knife.
The new cook, donned in a clean white apron, has a large knife in his hand that a butcher might use ready to cut up a chicken.
An amateur chef is a chef. Wearing something is being donned with it. Being about to chop something requires the knife to be in hand. A knife that a butcher might use is a butchers knife.
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