Playing college football for the UCLA Bruins, he was named a third-team All-American as a junior in 2015, when he also earned his second all-conference selection in the Pac-12.

He was rated by Rivals.com as a four-star recruit and committed to the University of California, Los Angeles (UCLA) to play college football.

[4][5][6] Already established as a strong run defender, he improved as a pass rusher as a junior after entering 2015 with just one career sack.

On September 25, 2016, he made his first career start against the Detroit Lions and racked up a total of four tackles in the Packer's win.

In Week 13 of the 2017 season, Clark recorded 1.5 sacks, his first of his NFL career and 6 combined tackles in a 26–20 overtime win over the Tampa Bay Buccaneers.

Clark had a breakout season in 2018, recording 55 tackles, three passes defensed, and six sacks, and was named a Pro Bowl alternate.

[21] In the Divisional Round of the playoffs against the Los Angeles Rams, Clark recorded 1.5 sacks on Jared Goff during the 32–18 win.