A number of people who play one or more instruments very well have become better known as singers, to the point that most fans never even knew about these stars' instrumental talents, which is a shame. I am stressing people who are truly masters/(near-)virtuosos on their instruments, not just mere dabblers. Let's list these folks from any genre of music. I'll start.
Phil Collins - masterful on the drum set
Karen Carpenter - also masterful on the drum set
Sheila E - masterful on latin percussion as well as the drum set
(I think this one has returned to her roots as a percussionist and has de-emphasized the singing part of her career. I haven't seen much of her since she quit running around in the street with Prince back in the 1980s.)
Nat King Cole - excellent jazz pianist before being marketed as a singer
Charo - "oochee coochee" girl is actually a trained and very talented flamenco guitarist
I'm sure people on this forum can give other examples that I don't know about.