Clarke will speak to Mulumbu tomorrow about his red card for petulantly kicking the ball at Gary O'Neil in injury time.
"I said to the group after the game that they must control their frustrations," the Scot said.
"It doesn't affect today's game but it affects our group and our squad and the next three games.
"We have a small group and it's a big loss for us.
"The time to speak about it is tomorrow. He probably did it out of frustration."