Feeling regret (5)
I believe the answer is:
sorry
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">feeling regret</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for sorry that I've seen before include "Feeling regret" , "Feeling penitent" , "Feeling penitence" , "I beg your pardon" , "Repentant" .)