What does "crack down" mean?

To take harsh action (against), as when enforcing a law more stringently than before.

What is a synonym for "crack down"?

Common synonyms include: clamp down, clamped.

/kɹæk ˈdaʊn/ verb

verb ·Rare ·Advanced level

Verb

1
To take harsh action (against), as when enforcing a law more stringently than before. idiomatic, often
"The authorities are trying to crack down on drunk driving during the holidays."
2
repress or suppress (something regarded as undesirable) wordnet

"The authorities are trying to crack down on drunk driving during the holidays."