"Regrettably ..." (4)
I believe the answer is:
alas
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">regrettably</span>' is the definition.<br/ ><span class="explanation-format__explanation">('alas' is said before regrettable news)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for alas that I've seen before include "By bad luck" , "Proper, respectable" , "What a shame!" , "Antipodean island state" , "Sad expression" .)