Biblical traitor (5)
I believe the answer is:
judas
'biblical traitor' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for judas that I've seen before include "The most notorious traitor of all" , "Apostle who betrayed Christ for 30 pieces of silver" , "The greatest betrayer" , "Disloyal person" , "Christian name of Iscariot, traitor" .)