Possible Clues:

• Not, by the sound of it, in size or in the mouth
• Large 16-Across
• Grinder of a sort
• Jaw protrusion
• Grinder of an amount of chemical matter
• A built-in food-processor
• It may be filled before it bites
• Seems that Doctor Laurence is the one for backbiting
• Certain grinder
• It inflicts grinding damage - nothing left inside