Judas's men kept under property (7)
I believe the answer is:
traitor
'judas's' is the definition.
(I've seen this in another clue)
'kept under property' is the wordplay.
'kept' becomes 'or' (I am not sure about this - if you are sure you should believe this answer much more).
'under' means one lot of letters go next to another (in a down clue, some letters go below others).
'property' becomes 'trait' (both can mean a quality or feature).
'or' after 'trait' is 'TRAITOR'.
'men' is the link.
This may not be right. It may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for traitor that I've seen before include "One committing treason" , "defector?" , "Rat riot (anag.)" , "One betraying one's country" , "Backstabber" .)