Corroborate in accordance with common authentication method (8)
I believe the answer is:
underpin
'corroborate' is the definition.
(I know that corroborate can be written as underpin)
'in accordance with common authentication method' is the wordplay.
I cannot really see how this works, but
'in' is within the answer.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for underpin that I've seen before include "Support or strengthen from beneath" , "Prop up with nun pride" , "Form the basis for" , "corroborate" , "buttress" .)