Transitory — death (7)
I believe the answer is:
passing
I believe this clue is a double definition.
'transitory' is the first definition.
(synonyms)
'death' is the second definition.
(passing is a kind of death)
(Other definitions for passing that I've seen before include "Ephemeral" , "Short-lived - death" , "Overtaking" , "Casual - death" .)