Clay, 23, previously played for Crusaders in 2012, on loan from Leigh, and scored 12 tries in 27 appearances for Barrow in 2013.
Coach Clive Griffiths said: “Adam is an out and out finisher and he certainly showed he pedigree when he was here on loan last year from Leigh Centurions. I had hoped we could secure his services for 2013, but when Barrow came in with the opportunity to play in the division above, I couldn’t really blame a player of his talents for wanting to be at the highest level he can get to.”
“With our promotion this season, it gave us the opportunity to offer Adam that level of Rugby and I’m delighted that he wanted to come, having enjoyed his spell so much in 2012. He’s an important capture as we build for life in the Championship.”
Clay previously came through the academy system at Salford.