McClellan began his college ice hockey at Mercyhurst during the 2020–21 season. During his freshman year he made six starts for the Lakers, and posted a 2–4–0 record, with a 2.03 goals against average (GAA) and .932 save percentage. He recorded his first career shutout on February 19, 2021, against Niagara. During the 2021–22 season, in his sophomore year, he made 26 starts, and posted a 12–13–2 record, with a 2.56 GAA and .932 save percentage.[1]
In April 2022, McClellan transferred to Wisconsin.[2] During the 2022–23 season, in his junior year, he served as backup goaltender to Jared Moe, and posted a 3–6–0 record in 12 starts, with a 3.57 GAA and .883 save percentage.[3]
During the 2023–24 season, in his senior year, he posted a 24–12–1 record, with a 1.94 GAA, and .931 save percentage. He helped lead Wisconsin from last place in the conference the previous year to the Big Ten Conference's runner-up and earned an NCAA Tournament berth. He led the NCAA with a .931 save percentage and seven shutouts, ranked second with a 1.94 GAA and fourth with 24 victories. His seven shutouts ranks second on Wisconsin's single-season list, one shy of the program record eight set by Brian Elliott in 2006. Following an outstanding season he was named All-Big Ten First Team, Big Ten Goaltender of the Year and a top-ten finalist for the Hobey Baker Award.[4][5] He was also named the Mike Richter Award winner and a AHCA West Second Team All-American.[6] He became the first Badger goaltender to be named an All-American since Brian Elliott in 2006.[7]
He finished his collegiate career with an overall record of 41–35–3, with a 2.35 GAA and .926 save percentage in 82 games.[8]