He played in Major League Baseball for the San Francisco Giants, St. Louis Cardinals, Texas Rangers, Chicago White Sox, Milwaukee Brewers, Colorado Rockies, Arizona Diamondbacks, Washington Nationals, Cincinnati Reds, Toronto Blue Jays, and Boston Red Sox between 1991 and 2007.

The Giants traded Clayton to the Cardinals, where he succeeded his childhood idol, Ozzie Smith, as their starting shortstop and made the All-Star Game in 1997.

[2] He has an older brother, Royal Jr.[3] Growing up in the middle class, Clayton's parents stressed academics, and did not allow him to play Little League Baseball until he was eight years old.

He played in the California Interscholastic Federation's Southern Section 1-A championship game at Dodger Stadium,[5] but lost to Whittier Christian High School.

[11] Starting the 1989 season with the Clinton Giants of the Class A Midwest League, Clayton struggled initially, batting below .200 by the end of May.

[22] Clayton batted .237 in 43 games for Phoenix, and was recalled to the major leagues on August 19 when Uribe went on the disabled list with a torn muscle in his rib cage.

[2][35] The Giants began to discuss trading Clayton to other teams after the 1995 season as they remained unable to agree to terms on a contract extension.

[33] Rich Aurilia was ready to become the Giants' starting shortstop and the team needed to improve their depth of pitchers.

They attempted to sign Walt Weiss and Greg Gagne, but neither wanted to play in a platoon with Smith, an all-time great.

[39][40] The Giants traded Clayton and a player to be named later to the St. Louis Cardinals for Doug Creek, Rich DeLucia, and Allen Watson on December 14, 1995.

[42] In his first year as the Cardinals' manager, Tony La Russa announced that Smith and Clayton would compete for the starting job in spring training in 1996.

[6][47] Clayton batted .277 with 33 stolen bases and a .972 fielding percentage, the fourth-best among National League shortstops, in 129 games played.

At the time, he was batting .261 with six home runs and 19 stolen bases, and had already exceeded his 1996 season totals in RBIs and extra-base hits with 36 and 31, respectively.

[47] Before the 1998 season, the Cardinals signed Clayton for a $3.5 million salary in his final year before becoming eligible for free agency.

[68] In May, Clayton wrote a blog post calling out Curtis, and Rangers manager Johnny Oates had them apologize to each other.

[74][75] Clayton batted .197 through the first 54 games of the 2002 season and was benched by White Sox manager Jerry Manuel in early June, who increased the playing time for Tony Graffanino.

[76] Only a week later, Manuel returned Clayton to the lineup at shortstop, alternating playing time with Valentín and Graffanino.

[77] At the end of July, Manuel decided that Valentín would receive the majority of playing time at shortstop for the remainder of the season.

[79][80] On December 11, 2002, the Milwaukee Brewers signed Clayton to a one-year contract worth $1.75 million for the 2003 season to succeed José Hernández as their starting shortstop.

[85] However, the Rockies did not resign Clayton, as they decided to give the starting shortstop role to Clint Barmes for the 2005 season.

[84] Clayton signed a one-year contract worth $1.35 million with the Arizona Diamondbacks for the 2005 season,[86] displacing Alex Cintrón as the starting shortstop.

[88] On February 2, 2006, Clayton signed a minor league contract with the Washington Nationals, who acquired him to serve as a backup to their incumbent starting shortstop, Cristian Guzmán, who had struggled during the 2005 season.

[89][90] The contract called for Clayton to earn $1 million if he made the team and another $250,000 available through incentives based on his playing time.

[91] Guzmán tore a muscle in his shoulder during spring training, and Clayton opened the 2006 season as the Nationals' starting shortstop.

[93] On July 13, 2006, the Nationals traded Clayton, Bill Bray, Brendan Harris, Gary Majewski, and Daryl Thompson to the Cincinnati Reds for Austin Kearns, Felipe López, and Ryan Wagner.

[96] However, the Blue Jays did not commit to having Clayton as their starting shortstop, saying that he would split playing time with Aaron Hill and John McDonald in the middle infield.

[101] They promoted him to the major leagues to provide infield depth behind starters Dustin Pedroia and Julio Lugo and backup Alex Cora on September 1, when rosters expanded.

[102] The Red Sox were the 11th team that Clayton played for, tying the record for position players set by Todd Zeile.

[35] On September 12, 2016, Clayton became the head varsity baseball coach for Oaks Christian School in Westlake Village, California.

[112] Clayton credited his wife with teaching him to keep his legs in condition for the longevity of his baseball career; he ran 200-meter (660 ft) sprints during the offseason to maintain his speed.