Regards as a noted agreement (4)
I believe the answer is:
eyes
'regards' is the definition.
(I've seen this before)
'a noted agreement' is the wordplay.
'a noted' becomes 'e' (I can't justify this - if you can you should believe this answer much more).
'agreement' becomes 'yes' (saying yes to something).
'e'+'yes'='EYES'
'as' is the link.
Can you help me to learn more?
(Other definitions for eyes that I've seen before include "(Paradoxical?) film with Cruise and Kidman" , "Openings" , "Scans" , "They see and" , "Looks at carefully" .)