Regretting (5)
I believe the answer is:
ruing
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">regretting</span>' is the definition.<br/ ><span class="explanation-format__explanation">('rue' can be a synonym of 'regret')</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for ruing that I've seen before include "Regretful" , "Bitterly regretting" , "Feeling sorry for" , "Having second thoughts" , "full of remorse?" .)