Updated: Aug 25, 2021
Clark Gregg appeared in "The Paley Center Presents Law & Order: Before They Were Stars" on Thursday, Nov. 12. It's an hour long special which aired after the Season 22 premiere of "Law & Order: SVU".
Clark played Patrick Dunne in Life Choice (season 1 episode 12), which aired 8 January 1991.
You can watch full special episode on NBC website.