After redshirting his first year at Penn State in 2017, Clifford spent 2018 as Trace McSorley's backup.

Clifford again was named an Academic All-Big Ten Conference honoree and earned a bachelor's degree in advertising and public relations following the 2020 fall semester.

He was honored in the 2021 NFF National Scholar-Athlete Class, selected to the Allstate AFCA Good Works Team, earned a spot on the Senior CLASS Award first team, named All-Big Ten honorable mention by the coaches and media, named Penn State's Big Ten Sportsmanship Award honoree, earned Academic All-Big Ten honors, and earned the team's Public Service and Lion's Pride Outstanding Senior Player Awards.

[9] He was named Big Ten Offensive Player of the Week twice (Purdue September 1, 2022; Minnesota October 22, 2022).

[14] He made his NFL debut on September 10, 2023, relieving Jordan Love in the closing minutes of a 38–20 win against the Chicago Bears; he attempted no passes and rushed the ball once for no gain.

[15] He did not see the field again until December 31, when he completed his first NFL pass attempt, a 37–yarder to Bo Melton, during a 33–10 win against the Minnesota Vikings.