First killer said to be crook (4)
I believe the answer is:
cane
'to be crook' is the definition.
(I've seen this in another clue)
I don't understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for cane that I've seen before include "Strong, flexible stem" , "Eg, bamboo; punish" , "Stick; thrash" , "Beat - bamboo - stick" , "Malacca, perhaps" .)