Dic: clamp (some of its meanings as a verb)

• Simon finished dialing and clamped the phone to his ear.
• He clamped his lips together.
• You beg him to try just one spoonful, and he clamps his mouth shut.
• Peter jumped to his feet with his hand clamped to his neck.
• If the government clamps down on the protestors, that will only serve to strengthen them in the long run.
• Banking regulators failed to clamp down until earlier this month.

VERB | To clamp something in a particular place means to put it or hold it there firmly and tightly.

PHRASAL VERB | To clamp down on people or activities means to take strong official action to stop or control them.[JOURNALISM] (= crack down)

.... Cobuild

CF. Clamp