Companion eliminating king's bad guy (5)
I believe the answer is:
fiend
'bad guy' is the definition.
(I've seen this in another clue)
I cannot understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for fiend that I've seen before include "Devilish person" , "Evil spirit, demon" , "monster" , "addict" , "Wicked and inhuman person" .)