Vesta and Pallas are among the solar system's largest ____s (8)
I believe the answer is:
asteroid
's' is the definition.
Although both the answer and definition are singular nouns, I can't see how they can define each other.
I don't understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for asteroid that I've seen before include "space traveller" , "Lump of rock orbiting the sun" , "could be dangerous for astronauts" , "Small heavenly body" , "Rocky body in orbit" .)