Fleeting (5)
'fleeting' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for ephemeral that I've seen before include "Lasting only briefly" , "life's too short" , "A mere help (anag) - short-lived" , "short term gain" , "Having only brief existence" .)
'fleeting' is the definition.
(I know that fleeting can be written as momentary)
This is the entire clue.
(Other definitions for momentary that I've seen before include "Short-lived" , "Brief" , "Fleeting" , "Lasting only a short time" .)
'fleeting' is the definition.
(similar in meaning)
This is the entire clue.
(Other definitions for short that I've seen before include "Not long enough" , "Terse; in insufficient supply" , "Wanting" , "Uncivil, brief film" , "Cause to blow a fuse" .)
(Other definitions for brief that I've seen before include "Concise; short-lived" , "Document stating the facts of a legal case" , "Remit" , "Fibre (anag.)" , "put in the picture" .)