The phrase "former champ" refers to someone who was once a champion or winner in a particular sport or competition, but is not currently holding that title. Full definition
Showtime Boxing: Highlights from James DeGale's unanimous decision victory and first defense of his IBF Super Middleweight World Title against former champ Lucian Bute on SHOWTIME CHAMPIONSHIP BOXING. (sho.com)
Dustin beat a declining former champ in Pettis, and Conor beat Aldo. (sbnation.com)
Newly crowned champion James «Chunky» DeGale (21 - 1, 14 KOs) takes on former champ Lucian «Le Tombeur» Bute (32 - 2, 25 KOs) in a battle for the super middleweight title. (sho.com)