Criminals used by shepherds? (6)
I believe the answer is:
crooks
'criminals' is the definition.
('crook' can be a synonym of 'criminal')
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for crooks that I've seen before include "at 16 down [MAN UNITED]" , "taken in hand by bishops" , "shepherds lay hold of" , "Bad guys" , "Cheats" .)