[2] As a freshman for the Louisville Cardinals, along with Derrick Caracter, Edgar Sosa, and Jerry Smith, the young group struggled early in the 2006–07 season.

Clark decided not to put his name in the 2008 NBA Draft and to return to the University of Louisville for the 2008–2009 season.

Clark was sent to the Iowa Energy of the NBA Development League on March 15, 2010, after only averaging 2.7 points, 1.1 rebounds, and 7.6 minutes in 45 games.

[5] On December 18, 2010, Clark was traded to the Orlando Magic along with Jason Richardson and Hedo Türkoğlu for Vince Carter, Marcin Gortat, Mickaël Piétrus, a 2011 first-round draft pick and $3 million cash.

The Denver Nuggets acquired Andre Iguodala, the Philadelphia 76ers received Andrew Bynum and Jason Richardson, and the Orlando Magic got Arron Afflalo, Al Harrington, Nikola Vučević, Maurice Harkless, Josh McRoberts, Christian Eyenga, and one protected future first-round pick from each of the other three teams.

[10] On January 9, 2013, Clark had a breakthrough night, playing 27 minutes and setting personal bests with 22 points and 13 rebounds against the San Antonio Spurs.

[15] On February 20, 2014, Clark was traded to the Philadelphia 76ers along with Henry Sims and two future second-round picks in exchange for Spencer Hawes.

[24] On October 31, 2014, Clark was acquired by the Iowa Energy of the NBA Development League as an affiliate player of the Memphis Grizzlies.

[26] On December 10, 2014, Clark signed with the Shandong Golden Stars of the Chinese Basketball Association after reaching a buyout with the Rio Grande Valley Vipers.

[33] Three days later, he made his debut for the 87ers in a 127–112 loss to the Westchester Knicks, recording four points, four rebounds, one assist, two steals and two blocks in 21 minutes off the bench.

[38] He also made the 2017 BSL All Star Game On June 16, 2018, Clark signed with Budućnost VOLI of the Montenegrin Basketball League for the 2018–19 season.

Having troubles to return to Spain during the lockdown to resume practice sessions,[42] San Pablo Burgos and Clark mutually decided to part ways on May 15, 2020.

[49] On September 13, 2024, Clark re-signed with the Hsinchu Toplus Lioneers of the Taiwan Professional Basketball League (TPBL).