clamp 1
1 to hold something tightly in a particular position so that it
does not move:
?
clamp sth over/between/around etc:
He clamped his hand over her mouth.2 BrE to fasten a piece of equipment onto the wheel of a car that has been parked illegally, so that it
cannot be moved; BOOT AmE
clamp down phrasal verb [I]
to become very strict in order to stop or limit something, especially criminal activity:
?
clamp down on:
The police are clamping down on drunk drivers.