Court procedure (4)
I believe the answer is:
oath
'court procedure' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for oath that I've seen before include "A word with a witness" , "swearing" , "A curse or solemn declaration" , "Curse or solemn word" , "Swearword, expletive" .)