The Radio 1 presenter, who was top of the leaderboard last week, dropped down to last place after her samba with partner Aljaž Skorjanec failed to impress judges Craig Revel Horwood, Shirley Ballas and Anton du Beke, who scored the routine just 18 points.
Kevin, who won Strictly with girlfriend Stacey Dooley in 2018 but has since left the show, said the judges were “harsh” on Clara and questioned their scoring of her fellow contestants.
In an Instagram Live broadcast Kevin said: “I thought the judges were so, so harsh on Clara and Aljaž. I really enjoyed their samba.”
He hailed Clara and Aljaž’s “timing, bounce [and] technique”, saying he was “really impressed” by the routine.
“Alright, there was a couple of mistakes that she made, but some of the other couples made mistakes as well,” he continued.
“My thoughts on it... you know when the judges go to some people, ‘Oh, there’s a couple of little bits that went wrong, but I loved it’, or, ‘Something went wrong there, but well done you for carrying on’.
“Yet with Clara, it was like, ‘You made a couple of mistakes’, and it was, ‘Nah, you made some mistakes’, and they slaughtered her.”
Kevin also questioned the number of nines being dished out, saying: “if Clara’s getting, like, a five and a six and a seven for hers – it wasn’t that far behind everyone to me.
“I thought the judges were really harsh on Clara and Aljaž, and I just love watching them.”
“I can’t understand why they were so harsh on Clara this week, I really can’t,” he later added.
“And people are gonna point to, ‘oh, she just went wrong on this bit’ or whatever, but I can point to things wrong with all the dances, y’know? Nothing’s ever going to be technically perfect, because they’re not professional dancers.”
Kevin also shared who he thought would be lifting the glitterball trophy this year.
“I still think Bill’s [Bailey] gonna win,” he added, “it’s gonna take a lot to stop Bill.”
Strictly Come Dancing continues this Saturday on BBC One.