Regulates decoys changing hands (5)
I believe the answer is:
rules
'hands' is the definition.
The answer and definition can be both man-made objects as well as being plural nouns.
Perhaps there's an association between them I don't understand?
I cannot understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for rules that I've seen before include "controls" , "following Queensberry?" , "Is king" , "is supreme, OK?" , "strips" .)