The fashion model - who was the first celebrity to be voted out of the show last year - explained that she wasn't a fan of the X Factor star.
"There have been moments where i've found him funny or endearing. I think he has a nasty steak (sic) though," she tweeted.
Lennard also criticised Clark for secretly leaving the Big Brother house in order to rehearse for the upcoming X Factor tour.
"Regardless he has cheated, broken the rules and been given a totally unfair advantage," she continued.
She added: "He should be removed from the final vote. It's just not fair on the other housemates who have played the game honestly. #justmyopinon #cbb."
> Celebrity Big Brother: Have Channel 5 gone too far with Rylan scandal?
Channel 5 bosses have explained that Clark's secret departures from the house were already agreed before the show as part of his contract.
Lacey Banghard has told Digital Spy that current housemates are aware of Clark's situation and have kept it a secret from the cameras.
Photo gallery - latest Celebrity Big Brother pictures: