On 17 February, he played off the interchange in a pre-season loss to the Wests Tigers, scoring a try.[7]
Clifford started the 2018 NRL season playing for North Queensland's Queensland Cup feeder side, the Northern Pride. On 16 April, he re-signed with the North Queensland club until the end of the 2020 NRL season.[8][9] On 24 June, he was 18th man for the Queensland Residents side.[10] On 11 July, he started at halfback for the Queensland U20 side, scoring two tries and being named Man of the Match in Queensland's first ever win.[11]
On 29 August, he was named Intrust Super Cup Halfback of the Year and Rookie of the Year at the QRL Gala Awards night.[13] On 13 September, he was named the Cowboys Rookie of the Year at the club's presentation ball.[14]
On 6 October, Clifford earned his first senior representative honours, starting at five-eighth in the Prime Minister's XIII's 34–16 win over Papua New Guinea.[15] A week later, on 13 October, Clifford captained the Junior Kangaroos to a 40–24 win over Junior Kiwis, being named Man of the Match.[16]
2019
Clifford entered the 2019 pre-season in a battle with Te Maire Martin for the vacant halves spot left by the retirement of Johnathan Thurston. Despite scoring a hat-trick in a pre-season trial against the Gold Coast Titans, Clifford lost out to Martin and began the season playing for the Northern Pride.[17] He made his season debut in a Round 3 loss to the Cronulla-Sutherland Sharks, playing five games before being dropped back to the Pride.[18] Clifford returned to first grade in the Cowboys' Round 12 win over the Gold Coast Titans. In Round 13, he scored his first NRL points, kicking four goals in a 20–22 loss to the Manly-Warringah Sea Eagles.
In Round 17, he scored his first NRL try and kicked the game winning field goal in North Queensland's Round 17 win over the Sydney Roosters.[19] In the Cowboys' Round 22 loss to the Newcastle Knights, Clifford suffered an ankle injury and missed the final three games of the season.[20]
On 16 December, Clifford re-signed with North Queensland until the end of the 2021 NRL season.[21]
In Round 3, he returned to first grade, playing 10 games at halfback before being dropped by interim head coach Josh Hannay after a Round 12 loss to the Canberra Raiders.[23][24] In Round 17, he was recalled to the side, scoring a try in North Queensland's win over the St George Illawarra Dragons.[25] Clifford finished the season as North Queensland's halfback, scoring a try in their Round 20 win over the Brisbane Broncos.[26]
In November, Clifford signed a two-year contract with the Newcastle Knights starting in 2022.[27]
2021
On 29 May, after playing seven games with the North Queensland club, Clifford secured an early release to join Newcastle for the remainder of the 2021 NRL season.[28]
He made his club debut in round 13 for Newcastle in a 40-4 loss against Parramatta.[29]
2022
Clifford made a total of 12 appearances for Newcastle in the 2022 NRL season scoring two tries as the club finished 14th on the table.[30]
On 27 October, Clifford signed a two-year deal to join English side Hull F.C. starting in 2023.[31]
2023
Clifford made his club debut for Hull F.C. in round 1 of the 2023 Super League season against Castleford which ended in a 32-30 victory.[32]
On 2 August, Clifford signed a one-year deal to return to one of his former clubs, North Queensland for the 2024 NRL season.[33]
Clifford played 25 games for Hull F.C. for in the Super League XXVIII season as the club finished 10th on the table.[34]
2024
Clifford was limited to only eight appearances with North Queensland in the 2024 NRL season which saw the club finish 5th on the table. He played in both the clubs finals matches as they were eliminated in the second week by Cronulla.[35]
