He played college football for the Georgia Bulldogs, and signed with the Washington Redskins as an undrafted free agent in 2003.

Clemons also played in the NFL for the Oakland Raiders, Philadelphia Eagles, Seattle Seahawks and the Jacksonville Jaguars.

Clemons signed with the Washington Redskins again for the 2005 season where he played in 14 games and had eight tackles, two sacks, a blocked punt, and a forced fumble.

[2] On March 16, 2010, Clemons was traded with a fourth round pick by the Eagles to the Seattle Seahawks in exchange for Darryl Tapp.

[3] He was originally brought in to play the Leo position in Pete Carroll's defensive 4–3 over scheme, but with the injury of Red Bryant after Week 7, Raheem Brock was moved into his place and Clemons moved to starting left defensive end.

On September 24, 2012, Clemons recorded four sacks, all in the first half, in a victory over the Green Bay Packers.

[4] On September 20, 2013, the Seahawks announced Clemons will play for his season debut in Week 3 against the Jacksonville Jaguars.