Lyons, known as Napper or Cliffy to his mates, started his rugby league career playing Lock forward, but was often moved into the Five-eighth role which is where he was considered to be at his best.

It was at five-eighth that Manly Warringah Sea Eagles coach Bob Fulton started playing Lyons on a permanent basis.

He made his first grade début for the Bears in Round 2 of the 1985 NSWRL season, playing five-eighth, and contributing a field goal in a 15–10 win over the Illawarra Steelers at the Wollongong Showground.

With Vautin fully recovered by the start of the 1987 season, Lyons became the Sea Eagles' first choice five-eighth alongside speedy Australian Kangaroos test half back Des Hasler.

At the end of the 1988 NSWRL season, Lyons made his international début when he was selected on the bench for a Rest of the World team that narrowly lost 30–28 to Great Britain at Headingley in Leeds, England.

Joining Lyons in the side were his Manly teammates Dale Shearer (Fullback), Michael O'Connor (Centre) and Noel "Crusher" Cleal (Second-row), as well as fellow Australians Steve Ella (5/8), Allan Langer (Halfback) and Sam Backo (Prop).

After winning the coveted Gold 'Dally M' award for Player of the Year in the regular club season he received his call-up to the Australian team on the 1990 Kangaroo Tour of Great Britain and France.

He repaid the faith shown in him by his former club coach Fulton by finishing one of the best team tries ever seen in a Test as Australia kept The Ashes alive with 14–10 win over Great Britain.

At the end of the 1991 NSWRL season Manly finished in 2nd place behind eventual premiers Penrith in the minor round, but bombed out in straight sets in the finals with losses to North Sydney and Canberra.

Lyons was then selected for the Australian national team for the 1991 Kangaroo tour of Papua New Guinea, regaining his test spot due to an injury to Jackson.