The Baggies boss dismissed suggestions that the 29-year-old centre-back has been affected by the ongoing discussions regarding his future at the Hawthorns
The 29-year-old's current deal expires at the end of the season but the Scot insists he remains focused on the task at hand.
“Jonas, in the matches he’s played since I’ve been here, has been terrific,” Clarke told reporters.
“It’s certainly not playing on his mind.”
Clarke is more concerned by the mounting number of injuries in his squad, with five first-team players unavailable ahead of the upcoming Premier League clash with QPR.
He added: “We gave quite a positive bulletin mid-week, unfortunately this game has come too quickly for some.
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“The players that have come in off the bench have always made a really positive contribution and we hope that will continue this weekend.
“Jerome [Thomas] started training this week but, unfortunately, the last two days he’s been off ill.
“He’s had a terrible time since I came here with one injury after another.
“All those have cleared up. Unfortunately he fell ill during the week and we are hopeful next week we can start right from the beginning and get some good work into Jerome.”
West Brom will welcome Peter Odemwingie back into the squad on Saturday following the end of his three-match suspension for kicking out at Fulham right-back Sascha Riether.
However, the former Liverpool assistant boss says the Nigeria international is by no means certain to regain his place in the first team.
“He should be concerned [about not being an automatic pick] because we have good players here," he continued.
“But he’s worked hard in training, he’s worked well but so have the other players. Peter will be in the squad and if he gets back into the side he’ll show what he can do.
“But he might have to wait to get his place back. There are no guarantees. He is available again. He has trained well.
“Peter has had to sit on the side-lines for the last three games through his own fault. He accepts that, he accepted that at the time and we just welcome him back to the squad.”