Verification (13)
'verification' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for proof that I've seen before include "Strength of spirit" , "Testimony" , "Convincing evidence" , "Clear evidence" , "mathematical tour de force" .)
'verification' is the definition.
(corroboration is a kind of verification)
This is all the clue.
(Other definitions for corroboration that I've seen before include "Further proof" , "Confirmation" .)