Magistrates are to be set on! (5)
I believe the answer is:
bench
'set on' is the definition.
The answer and definition can be both man-made objects as well as being singular nouns.
Maybe there's an association between them I don't understand?
'magistrates are to be' is the wordplay.
I cannot really see how this works, but
'be' is present in the answer.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for bench that I've seen before include "Magistrates collectively" , "Pew or settle" , "Exhibit at dog show" , "Long seat for judges" , "Group of magistrates" .)