Claggett joined D’Arcy Masius Benton & Bowles (DMB&B) in St. Louis as a writer and producer in 1972. From 1985 to 1989, he served as Executive VP and Creative Director in the agency’s London office, helping to launch Budweiser in the U.K. and relaunch Wiskas Cat Food, the largest grocery brand in the UK. Claggett was promoted to Chief Creative Officer in the St. Louis office in 1989 and to Managing Director Chief Creative Officer in 1994, positions he held until he left DMB&B in 1999.He created and oversaw the creative work for major clients, including Anheuser-Busch, Coca-Cola, Ralston Purina, Southwestern Bell (now AT&T), Blockbuster, Mars, and others. He served on D’Arcy’s worldwide board of directors and managed the St. Louis office with billings exceeding $300 million. 

From 1997 to 1999, he also served as Global Creative Director at D’Arcy Worldwide on the agency’s Coca-Cola business, creating advertising for Coke brands, including Georgia Coffee in Japan, Fanta in Germany, and Fanta in Mexico. 

Claggett’s work earned him over 80 national and international creative awards, including Cannes Lions, Clios, and International Broadcasting Awards. In 1985, he was named one of the top 100 “Brightest and Best” people in advertising by Advertising Age. In 2008, he was inducted into the St. Louis Media History Hall of Fame.