Thompkins will join fellow Nittany Lion Saeed Blacknall in the Steelers' receiving corps.
Clifford hauled in nine catches for 125 yards in a tough 30-24 overtime loss to Brownsburg on ESPN.
Blacknall has re-signed with the Steelers after being released by the organization one week ago.
The Big Ten is considering playing a schedule that would start the week of Thanksgiving, per a report by the Milwaukee Journal Sentinel's Jeff Potrykus.
BTN will air two Penn State classics from the 2016 season on Thursday night.
With seemingly more Nittany Lions in the NFL than ever, there’s no better time to draft some former Penn State stars to your fantasy teams.