Clarke was impressed by the on-loan Dynamo Kiev left-back's introduction to English football.
"I thought Goran Popov came in on his debut to play in a game like that and showed the qualities he's got," he told the WBA website.
"We had no doubts he would be able to handle the game.
"He's an experienced player, has played in a lot of big matches, and he showed that today.
"He's got a terrific left foot, knows the game, knows how to defend, and is a strong boy.
"He gives us another good option in the squad."