He scored his first Ontario Hockey League (OHL) goal and assist in the third game of the 2017–18 season, on September 24, 2017, against the Erie Otters.

On January 21, 2018, he scored a Michigan goal against the Peterborough Petes, a move he had done successfully multiple times prior to his OHL career.

[12] In the playoffs, Clarke put up six points in as many games, as the Comets were once again eliminated in the second round, this time by the Toronto Marlies.

[17] Clarke represented Canada at the 2018 Hlinka Gretzky Cup, scoring three points in five games en route to a gold medal.

His brother Brandt was selected eighth overall by the Los Angeles Kings in the 2021 NHL Entry Draft,[18] while his sister Mackenzie plays for St. Lawrence University.