Thomas was stood down from the club earlier this year after allegations of inappropriate behaviour towards women, before a video surfaced on social media of the 23-year-old driving recklessly which prompted a further delay to his return.
The Roo has been training with the VFL program since April, with Sunday marking his return to the field, collecting 18 disposals in the 66-point win.
"He performed well in his first game back ... so he's just building his match fitness," Clarkson said.
"He's got another week in the VFL program, I'm led to believe, and then he'll be back in the AFL program.
"Once he's back in the AFL program we'll just see what his fitness level and match conditioning is like.
"If he continues to do what we require him to do then hopefully he'll be available for selection pretty soon."
The 23-year-old was charged earlier this year with threatening to distribute an intimate image and faced court in March, with his next court appearance scheduled for July.
North have required Thomas to undergo a respect and responsibility education program and work part-time since being stood down by the club.
"I've seen very little of Tarryn since he's been out of the AFL program and that will hopefully ramp up a little bit next week," Clarkson said.
"Once he gets back into it, I'll just more or less focus on his footy and what he needs to do there.
"The footy side of it, for mine, is what his fitness base is like and how many games does he need to play to get cherry ripe to be able to play senior AFL footy.
"We'll make that determination and the rest of the stuff Jen and Todd will look after off to the side."
Thomas has played 57 senior games for the Kangaroos since making his debut in Round 2, 2019.