Subdue one of the herd (3)
I believe the answer is:
cow
'subdue' is the definition.
(as in cowing someone into submission)
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for cow that I've seen before include "Subdue with threats or force" , "Subdue in bovine manner?" , "Unnerve" , "Frighten with intimidations" , "Browbeat" .)