Wiktionary
vb. to enforce laws or punish (something) more vigilantly
Usage examples of "crack down on".
This week, the Dade State Attorney's Office and the lieutenant governor announced an ambitious plan to crack down on crooked builders.
The Falun Gong group hadn't even been a religion at all, not to Nomuri's way of thinking, but for some reason he didn't fully understand, it had frightened the powers that be in the PRC enough to crack down on it as if it had been a genuinely counterrevolutionary political movement.
That's why they'll crack down on you, while they'd let another man off.
It is not enough to crack down on these so-called American mercenaries fighting against their own country in the paid service of the armed forces of Libya, Chad and Syria.
You may have been so transparently disguised that your position would be revealed and your family would crack down on you.
If we crack down on Aco and Numenius, that'll send a clear message to the other malingerers.
They're going to crack down on you for signing Washington Irving's name to all those letters you've been signing Washington Irving's name to.