I'd say it's more likely Gueye he replaces. Notable that when Clarkson came on it was in a deeper role (granted, he was replacing Palaversa and Shinnie was being used at left back) but I think Thelin feels Nisbet playing off someone a bit more mobile, with the two wide men cutting in, is the way to go.
Nisbet I thought was again excellent. I'd be inclined to start him and Dabbagh on Tuesday.
Morris was good when he came on. It's funny though, it's so predictable what he's going to do - he'll always go to his right when a defender stands him up. But, he's tenacious and is holding onto the ball well under pressure.
Tobers and Knoester. We've finally got a good defensive partnership there.