Depart at a later date than (7)
I believe the answer is:
outlive
'depart' is the definition.
The answer and definition can be both to do with fundamental existence as well as being verbs in their base form.
Perhaps there's an association between them I don't understand?
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for outlive that I've seen before include "Die after" , "Survive beyond (another)" , "weather" , "Go on longer than" , "Survive longer than" .)