All three are newcomers. The Chargers agreed to terms of a two-year contract with one of their own unrestricted free agents, linebacker Reggie Walker.
Clemens will take over for Charlie Whitehurst, an unrestricted free agent who signed with Tennessee.
Clemens spent the last two seasons with the St. Louis Rams as a backup to starter Sam Bradford. Clemens started the last nine games after Bradford went down with a knee injury, completing 142 of 242 passes for 1,673 yards and eight touchdowns, with seven interceptions.
Clemens was selected by the New York Jets in the second round of the 2006 draft. He signed with Washington in 2011, was released at the end of training camp and he later signed with Houston. He was claimed by the Rams after being waived that December.
Conner is the second former Colts player to sign with the Chargers in the last three days, joining running back Donald Brown, who signed with the Chargers on Tuesday.
Chargers general manager Tom Telesco was with the Colts' front office when Conner was drafted in 2010.
Conner started 36 of 52 games played in four seasons with the Colts. He had 236 tackles, a sack and two forced fumbles, including a 104-tackle season in 2011 when he played in all 16 games, with 15 starts.
Ghee joins the Chargers after playing four seasons with Cincinnati. He played in 10 games last season and has played in 23 games during his career. He missed the 2012 season due to a wrist injury.
Talk about all of San Diego's free agent moves inside the message boards.
Conner, Clemens get deals
BoltsReport Top Stories
NFL Mock Draft 1.0 Picks 1-10Former Scout Fantasy writer Scott Gallimore joins Dolphins Report Publisher Eric Roddy in a post Free Agency mock draft. Here are the first 10 picks.
Dolphins ReportMonday at 3:30 AM
Finding Broncos: Jahad Thomas, RBWith another running back on the docket, Senior Draft Analyst Erick Trickel breaks down Temple's Jahad Thomas.
Mile High HuddleSunday at 5:25 PM
3 Reasons Denver Should Pass On McCaffreyBroncos fans are pining for Stanford's Christian McCaffrey but Adam Uribes makes the case for Denver avoiding the electric running back.
Mile High HuddleFriday at 7:48 AM
Rams sign defensive lineman Tyrunn WalkerThe addition of Walker brings more depth to the interior of the defensive line.
LA Rams Report03/23/2017
Finding Broncos: De'Angelo Henderson, RBNext up for the “Finding Broncos” scouting reports is a smaller school prospect named De’Angelo Henderson.
Mile High Huddle03/22/2017