Some twelve-stone sprites (5)
I believe the answer is:
elves
'sprites' is the definition.
(elf is a kind of sprite)
'some twelve-stone' is the wordplay.
'some' indicates a hidden word (some of the parts of the word are used).
'ELVES' is hidden in the letters of 'twelve stone'.
(Other definitions for elves that I've seen before include "Supernatural creatures" , "Fairy-like beings" , "Mythical beings" , "Little mischievous fairies" , "Troublemakers" .)