"Regrettably ..." (4)
I believe the answer is:
alas
'regrettably' is the definition.
('alas' is said before regrettable information)
This is the entire clue.
(Other definitions for alas that I've seen before include "By bad luck" , "Proper, respectable" , "What a shame!" , "Antipodean island state" , "Sad expression" .)