Possible Clues:

• Wheel in turnstiles
• A toolmaker may produce one, setting one's teeth on edge
• The cart collapses: one's teeth are set on edge!
• Red mullet's tail taken by rodent that has teeth
• Increase incrementally, with 'up'
• Damaged the cart's wheel? Maybe
• Device that allows movement in one direction only
• Mechanical device preventing a wheel slipping backwards
• Set of teeth chatter uncontrollably
• Pawl engager