Extremely old (7)
I believe the answer is:
archaic
'extremely old' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for archaic that I've seen before include "Belonging to former or ancient times" , "Ancient or out of date" , "Belonging to former times like some words" , "A long way out of date" , "Outdated" .)