#*!@ state under oath (5)
I believe the answer is:
swear
'state under oath' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for swear that I've seen before include "Avow" , "Express annoyance" , "Utter obscenities or take an oath" , "not to mince one's words" , "Vow; blaspheme" .)