2007-08: Adam Clendening played for the Toronto Marlboros Midget AAA club, scoring 8 goals and adding 42 assists for 50 points while compiling 116 penalty minutes.
2008-09: Clendening split time between the U.S. NTDP U-17 and U-18 squads. In 39 games for the U-17 team, Clendening scored 1 goal and added 13 assists for 14 points. In 23 games for the U-18 team, Clendening scored 1 goal and added 4 assists for 5 points. Clendening played for the USA’s gold medal squad at the 2009 U-18 World Junior Championship, picking up 2 assists in 7 games.
2009-10: Clendening split time between the U.S. NTDP U-18 national squad and the team that competed in the USHL. In 65 games for the U-18 team, Clendening scored 14 goals and added 35 assists for 49 points to go along with 120 penalty minutes. In 26 games for the USHL squad, Clendening scored 4 goals and added 13 assists for 17 points to go along with 44 penalty minutes. Played for the USA’s gold medal squad at the 2010 U-18 World Junior Championship, scoring 3 goals and adding 7 assists for 10 points in 7 games. He was named to the tournament All-Star Team for his efforts.
2010-11: In his freshman season at Boston University, Clendening played in 39 games for the Terriers. He scored 5 goals and added 21 assists for 26 points to go along with 80 penalty minutes. Clendening was named to Hockey East All-Rookie Team. Clendening was shosen in the second round, 36th overall, of the 2011 NHL Draft by the Chicago Blackhawks.
2011-12: Clendening was the leading scorer among defensemen for Boston University as a sophomore and represented the USA at the 2012 U20 World Junior Championship along with fellow Blackhawks prospect Stephen Johns. In 38 games for the Terriers he scored 4 goals with 29 assists and was plus-11 with 64 penalty minutes. After finishing tied for second in Hockey East the Terriers lost to Maine in the Hockey East tournament semifinals. Boston University received an at-large bid to the NCAA tournament; falling to Minnesota in the West Regional semifinals. In six games at the WJC, Clendening scored 1 goal with 4 assists and had 6 penalty minutes on a USA team that finished seventh in the ten-team tournament. In June 2012 he signed a three-year entry-level contract with the Blackhawks; foregoing his final two years of college hockey.
2012-13: Clending was the top offensive defensemen for Chicago’s AHL affiliate Rockford in his first pro season. He scored 9 goals and was second on the IceHogs with 37 assists; finishing +17 with 67 penalty minutes in 73 games. Rockford finished third in the Midwest Division, two points behind Milwaukee for the final Western Conference playoff spot.
2013-14: Clendening once again led Chicago AHL affiliate Rockford in scoring in his second pro season. Skating in 74 of 76 games for the IceHogs he scored 12 goals with a team-high 47 assists and was plus-5 with 64 penalty minutes. Rockford missed the AHL playoffs; finishing fourth in the Midwest Division. Clendening was named to the AHL first all-star team.
Clendening is an offensive defenseman with good puck-moving ability and a solid shot from the point. While he is known for his offensive and ability to transition the puck up ice, Clendening is solid defensively. He doesn't shy away from the physical side of the game and plays with a good deal of intensity. However, Clendening could stand to utilize his intensity and grit more to the benefit of his team. He also needs to keep his feet moving and improve his overall speed.
Clendening was dealt yet again, this time along with David Perron by the Pittsburgh Penguins to the Anaheim Ducks for Carl Hagelin. Clendening ws then put on waivers by the Ducks, but was claimed by the Edmonton Oilers.