"Such a shame!" (4)
I believe the answer is:
alas
'such a shame' 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 "Regretfully!" , "'- Poor Yorick' (Hamlet)" , "Too bad, so sad" , "Expression of grief or misfortune" , "Expression of regret" .)