clamp down on

phrasal verb

clamped down on; clamping down on; clamps down on

1

: to try harder to punish (people who are doing something that is not legal or proper)

Customs officials are clamping down on smugglers.

The school should clamp down on students who cut classes.

2

: to work harder to stop (a crime)

The state is clamping down on drug trafficking.