Cruel ones (7)
I believe the answer is:
sadists
'cruel ones' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for sadists that I've seen before include "Perverted pain-inflicters" , "They take pleasure form inflicting pain" , "They like to hurt" , "People who enjoy inflicting pain on others" , "people with a mean streak" .)