Woe is me! (4)
I believe the answer is:
alas
'woe is me' 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 "Exclamation of misfortune" , "'- Poor Yorick' (Hamlet)" , "More's the pity" , "express regret thus" , "Unhappily" .)