The definition of crackdown is the strict enforcement of specific rules.
If your boss is tired of everyone being late and makes an announcement that the next person who is late is going to be fired, this is an example of acrackdown.
a resorting to strict or stricter measures of discipline or punishment
An act or example of forceful regulation, repression, or restraint: a crackdown on crime.
Noun use of the verb “to crack down”