The loose forward-cum-lock is best known for his dominant performances for Pirates over the years.
But with his old club pulling out of the premier grade this season, Clark joined several of his teammates, including Otago props Craig Millar and Hisa Sasagi, in making the move to Southern.
It has given the Magpies an almighty forward pack and they used all that brute force to beat University 25-24 at Logan Park on Saturday.
As always, Clark was hugely influential in the lineouts. He is a great leaper and teamed up with Kyle Harris to help Southern dominate that aspect of the game.
"We always knew Josh [Dickson] was going to be one of the ball winners so we just marked up on him and put pressure on their hooker. We stole some of their pill, which probably helped us in the long run."
Southern led 25-10 but University roared back with two converted tries in the last 10 minutes to salvage a bonus point. It caused a few palpitations in the Southern camp.
"We always knew they were going to come back with a bit of a hiss. They are a fit young side and we just had to try and do them up front early on and it sort of worked."
Southern has not played with a lot of width this season but did tweak its game plan a little, Clark said.
"We’ve been using our size to get across and not using any of our skill. So it was good to see the backs actually running with some ball [on Saturday].
"Our forward pack has been quite greedy and trying to do everything because we had this expectation that we were the team to beat.
"Teams have rattled us and we would get flustered and we’d being doing one-off runs and never really gave our backs any ball. But the last few trainings we’ve been letting our backs have some fun."
It is hard to see Southern moving too far away from its usual game plan when it puts its unbeaten record on the line against Green Island at Bathgate Park, though.
Clark was enjoying his stint with Southern but was bitterly disappointed when Pirates decided not to field a premier team.
"It is a bit sad. There are some good players that have gone elsewhere but I’m pretty sure they will come back next year or the year after, and hopefully I can have a few more games for them.
"But at the moment I’m a Southern man so I will just keep chipping away for them."
Clark was further south last year. He signed a one-year deal for Southland and played seven games for the Stags. He is still in talks about returning this season but is just focused on club rugby at this stage.