Vows having been given to an orderly I didn't know about (2,4)
I believe the answer is:
on oath
'vows having been given to an orderly i didn't know' is the definition.
I know nothing about this answer so I can't judge whether this works.
'about' is the wordplay.
I cannot quite understand how this works, but
'about' could be 'on' and 'on' is present in the answer.
The remaining letters 'oath' is a valid word which might be clued in a way I don't understand.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for on oath that I've seen before include "Bound to speak the truth" , "Sworn to speak the truth" .)