Estus joined the R&B band Brainstorm as a teenager, recording two albums with them and scoring a hit with "Popcorn." During the early 1980s, he appeared as a session bassist on several mainstream albums, including Marvin Gaye's 1982 comeback album, Midnight Love. After his bass talents were recognized, he was invited to join the UKpop group, Wham!. He went on to tour China with Wham! and later backed Wham! frontman George Michael on his Faith tour. He also participated in the late-1980s collective, Boogie Box High, which was spearheaded by George Michael's cousin, Andros Georgiou, and featured Michael along with other high-profile musicians; Estus appears on the group's only album, Outrageous, released in 1989. Estus later performed with Michael at Rock in Rio and has continued to play bass as part of Michael's backing band.
In 1989, Estus released a soloalbum entitled Spell, produced by Colin Campsie & George McFarlane, with several tracks produced by George Michael. Released before the album, the single "Me or the Rumours" reached #15 on Billboard's Hot Dance Music/Club Play charts in 1988. In 1989, the album's title track hit #11 on the Adult Contemporary charts. However, the album's biggest hit was the #5 Billboard Hot 100single "Heaven Help Me," for which Michael supplied backing vocals. It also peaked at #3 on both the Adult Contemporary and Hot R&B charts. The album itself ultimately reached #89 on the Billboard 200 and #44 on the Top R&B Albums charts.