Already dealing with a core-muscle injury since Week 10, Clowney missed practice Wednesday and Thursday with an illness and returned Friday as a limited participant. The team initially listed him as questionable before downgrading him to out.
The Seahawks (10-3) could be down a pair of pass-rushers against the Panthers (5-8). Ezekiel Ansah, who missed the Seahawks' Sunday night loss to the Rams with a neck injury, is questionable to play at Carolina and will be a game-time decision.
Prior to Clowney being ruled out, coach Pete Carroll said the defensive end had been "pretty sick" this week but sounded hopeful he'd be OK by Sunday. Several Seahawks players have gotten sick since the week of Thanksgiving.
Clowney is tied for the team lead with three sacks this season and ranks fifth in the NFL in ESPN's pass rush win rate at 25.1%. He missed the team's win over Philadelphia in Week 12 because of his core-muscle injury, which is something he said he'll have to manage for the remainder of the season after deciding to put off surgery.
Wide receiver Tyler Lockett (shin) was listed as a full participant Wednesday and Thursday.