Clarke clarified the situation at his Friday morning press conference.
"Obviously Nicolas lost a close friend and an agent over the weekend - he died suddenly," he said.
"I had a very brief chat with him, and he wasn't in a good place. So the club have decided just to give him a bit of time to go away and think about it and get himself in a better place for the future.
"Really, that is as much as there is to tell on the situation. It wasn't dramatic, there was no big bust-up, he didn't storm out of the training ground. It is just a boy who is really quite upset."