Clam up and Clamp down

Clam up verb - To stop talking.

Clamp down and clam up are semantically related in prevent topic. In some cases you can use "Clamp down" instead a verb "Clam up".

Clamp down verb - Repress or suppress (something regarded as undesirable).

Clam up and clamp down are semantically related in prevent topic. Sometimes you can use "Clam up" instead a verb "Clamp down".