Viewed as I'd mentioned (4)
I believe the answer is:
eyed
'viewed' is the definition.
(I've seen this before)
'i'd mentioned' is the wordplay.
'mentioned' shows a homophone (sound like).
'id' is a homophone of 'EYED'.
'as' acts as a link.
(Other definitions for eyed that I've seen before include "Saw" , "Looked at closely" , "Stared at" , "Spotted" , "examined" .)