clamp

clamp verb clamps; clamped; clamp·ing

[+ obj] 1 : to hold or press (things or parts of a thing) tightly together with a device : to fasten or tighten (something) with a clamp
▪ The surgeon clamped the vein. ▪ He clamped the two pieces of wood together.

2 : to press or squeeze (something)
▪ The bit was clamped firmly between the horse's teeth. ▪ He clamped his mouth shut and refused to speak.

3 Brit : ²boot 4

clamp down on [phrasal verb]

clamp down on (someone or something) : to try harder to punish (people who are doing something that is not legal or proper)
▪ Customs officials are clamping down on [=cracking down on] smugglers. ▪ The school should clamp down on students who cut classes. : to work harder to stop (a crime) ▪ The state is clamping down on [=cracking down on] drug trafficking. — see also clampdown

clamp on

[phrasal verb] chiefly US clamp (something) on (something or someone) : to officially set (a limit, rule, punishment, etc.) for (someone or something)
▪ The mayor clamped [=imposed] a curfew on the area after the riots. ▪ The new law clamps limits on the amount of money candidates can spend on election campaigns.