Oath I for one said out loud (6)
I believe the answer is:
avowal
'oath' is the definition.
(I've seen this in another clue)
I don't understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for avowal that I've seen before include "Open assertion" , "Statement" , "swear!" , "acknowledgement" , "Positive declaration" .)