See a line I saw confirmed (9)
I believe the answer is:
validated
'confirmed' is the definition.
(validating is a kind of confirming)
'see a line i saw' is the wordplay.
'see' becomes 'v' (Latin 'vide', used to direct a reader to a source).
'line' becomes 'l'.
'saw' becomes 'dated' ('date' can be a synonym of 'see'**).
'v'+'a'+'l'+'i'+'dated'='VALIDATED'
(Other definitions for validated that I've seen before include "proved true" , "backed up" , "certified" .)