Born in Jonesboro, Arkansas to Tim Clemons and Valarie Hilson, he grew up in a family with a history of track and field – his mother competed in track for Arkansas State University. He attended Rowlett High School and had his first regional track competitions there, winning state high school titles twice in the 400 m and twice in the 4×100-meter relay. He left high school with a personal record of 46.35 seconds for the 400 m. After graduation, he went to the University of Kansas to study for a degree in African and African-American studies. In his first season of competition for the Kansas Jayhawks collegiate team, he won at the Kansas Relays and achieved a personal record of 45.98 seconds at the NCAA qualifier meet. He came sixth at the Big 12 Conference championship and was a semi-finalist at the NCAA Men's Outdoor Track and Field Championship, where he also competed with the 4×400-meter relay team. In addition to this he entered the senior national event and was a semi-finalist at the 2010 USA Outdoor Track and Field Championships. His second year did not see much improvement. He again won at the Kansas Relays, but was out of the top three at the Big 12 Conference indoor and outdoor meets and his season's best of 46.11 seconds saw him eliminated in the first round of the NCAA Outdoor Championship. Clemons came ninth at the 2012 Big 12 Conference Indoor Championship, but had greater success outdoors. He ran a personal best of 45.91 seconds to take third in the 400 m at the Big 12 outdoor meet and also came fourth in the 4×400 m relay, helping set the second fastest time ever for the school at 3:04.89 minutes. Another personal record of 45.44 seconds at the NCAA Outdoors brought him to second on the all-time school lists. He entered the 2012 United States Olympic Trials but did not get past the first round. In his fourth and final year at Kansas, he broke Deon Hogan's long-standing school records from the early 1980s with an indoor best of 46.44 seconds and an outdoor best of 45.10 seconds. At the Big 12 indoor meet he came third in the 400 m and second in the 4×400 m relay. He bettered this at the Big 12 outdoors, winning both individual and relay titles, running alongside DeMario Johnson, Michael Stigler, and Kenneth McCuin. He was a semi-finalist in both events at the NCAA Outdoor Championship.
Professional
In his first professional season in 2014, he won his first national title at the USA Indoor Track and Field Championships, beating the more experienced David Verburg to become the USA 400 m champion with an indoor personal record of 45.60 seconds. This performance led to his selection for the 2014 IAAF World Indoor Championships. At the event, his first major championship, he was the second fastest in qualifying for the final then finished third in the final, taking the bronze medal.
