Typically any player that is cut, the guaranteed money accelerates into the cap. If done after June 1 the hit can be spread over 2 years. Whether additional relief can be had depends on any offset language in the specific contract. KC would have to show the player violated that portion of the contract and the union almost always files a grievance even then, which may take a few years in arbitration, and usually results in some sort of compromise.
This is different than the league process. In that, he has violated league conduct policy which specifically mentions illegal possession of a firearm or weapon. Even with 2 violations that likely would only result in counseling and suspensions from the league since it wasn't a violent crime. Possibly he would be placed on the commissioners exempt list.
For Clark, his 2021 salary fully guaranteed in March. Future guarantees may be able to be recovered though since there is an out built into the contract after this year.