Passing through keeper's trim fringe with a lot of time left (9)
I believe the answer is:
ephemeral
But I can't explain it at all! Could you help me understand?
(Other definitions for ephemeral that I've seen before include "short term gain" , "Having only brief existence" , "A mere help (anag) - short-lived" , "life's too short" , "not going to last long" .)