The Burundi-born England Under-21 striker has netted five times in seven matches this season, including a hat-trick on his first start for the club in the 3-0 Capital One Cup victory over Newport County in August.
His impressive form has reportedly caught the eye of Chelsea, but manager Clarke dismissed talk of a move and expects Berahino to commit his future to West Brom.
Speaking at the Asian Football Awards, Clarke said: "It's just speculation and the speculation is rubbish.
"He's under contract with West Brom until the end of next season, so we've got plenty of time to sort out Saido's future.
"He's a sensible boy. He understands that all the rewards and riches come with hard work and he has to just concentrate on his football and let other people worry about his contract situation and whatever.
"Saido has got a big future in the game and all he can do now is work hard and make sure he is still a top player in 10 years' time."
Berahino has already scored against Arsenal and Manchester United this season and Clarke is pleased the 20-year-old has seized his first-team opportunity.
"It's no big surprise with Saido," he said.
"He trained with the first team in pre-season last year then went on loan in the Championship to get to some good experience at Peterborough but unfortunately he picked up a bad injury and he was out for seven months.
"But he's had another great pre-season with us and has forced his way into the first-team reckoning."