Clay was born Thomas Clague in New York, and in the 1950s he was popular in the Detroit area on WJBK-AM both as a DJ, and for his on-air comic characterizations; he became a local celebrity. In the early 1950s Clay, using the pseudonym "Guy King," worked for WWOL-AM/FM in Buffalo, New York; on July 3, 1955, he conducted a stunt in which he played "Rock Around the Clock" by Bill Haley & His Comets repeatedly from atop a billboard in Buffalo's Shelton Square, an incident that led to his firing and arrest.
He was caught up in the payola scandal of the late 1950s, and admitted to having accepted thousands of dollars for playing certain records. After being fired from WJBK, Clay worked at the short-lived Detroit Top 40 station WQTE (now WRDT) only to be fired again when the station changed format to easy listening music in 1961. After moving to Los Angeles to work at KDAY, Clay returned to the Detroit area and found work at CKLW in neighboring Windsor, Ontario, at the time one of the foremost Top 40 AM stations in North America.
Riding the wave of early Beatlemania he again rose in popularity, met and interviewed The Beatles. He was fired over a scheme in which he invited listeners to send in one dollar for membership in a "Beatles Booster Club", an essentially non-existent organization which had no benefits beyond a promised membership card or decal. According to fellow CKLW DJ Dave Shafer (also now deceased), Clay also promised each listener who sent in a dollar a personal item used by one of the Beatles; these "personal items" turned out to be items such as cigarette butts and used tissues, and other listeners claimed to have received nothing. However, since over 80,000 fans responded, Clay was able to live comfortably for a time on the cash that appeared in his personal post office box. Dave Shafer told David Carson in Rockin' Down the Dial that Clay skipped town in the wake of the Beatles Booster fiasco, leading to Shafer's being briefly jailed on charges of international fraud. Clay eventually returned to work at other Detroit area radio stations, including WWWW-FM, and also worked at WCBS-FM in New York. In 1984, he played pop standards at KPRZ, Los Angeles.
Clay is best remembered for his single on Motown's MoWest label "What the World Needs Now Is Love"/"Abraham, Martin and John" (MoWest MW5002F), a compilation of clips from the two popular records, interviews, and speeches of Jack and Bobby Kennedy and Martin Luther King emphasizing tolerance and civil rights. It went to #8 on the Billboard Hot 100. It sold over one million copies, and was awarded a gold disc.
A follow-up album had respectable sales, but another single, "Whatever Happened To Love" (MoWest MW5007F), flopped, and Clay found himself unemployed. Both songs were featured on the MoWest album What The World Needs Now (MS 103-L, released August 1971). Clay finished his career doing voiceover work.
Clay died of stomach and lung cancer at the age of 66, in Valley Village, Los Angeles, California in 1995.