Brown, 16, made his debut on Saturday.
Clarke said: "It's great for Izzy and it's good for the club. It's important that we show there is a path from the academy to the first team.
"Isaiah trains with the group. He's been with the group for a number of weeks and he's done well. It's a first full step in what could be a good career for the boy.
"Last pre-season I combined the first-team and under-21 squad. We worked for the first full week as a group and there were 27 or 28 players at times.
"That will be very similar next season and Izzy will be involved.
"It's important that we don't over-hype Izzy. He's got his career in front of him and on Saturday he took a first small step in what is hopefully going to be a very good career for him."