"C'est la vie" (4)
I believe the answer is:
alas
'c'est la vie' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for alas that I've seen before include "Antipodean island state" , "Regrettably, unfortunately" , "Lackaday" , "Expression of regret" , "What a shame!" .)