Overtaking is temporary (7)
I believe the answer is:
passing
This clue is a double definition.
'overtaking' is the first definition.
('pass' can be a synonym of 'overtake')
'temporary' is the second definition.
('passing' can be similar in meaning to 'temporary')
'is' is the link.
(Other definitions for passing that I've seen before include "Ephemeral" , "Casual - death" , "Overtaking" , "Short-lived - death" .)