Wallop but good (4)
I believe the answer is:
drub
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">wallop but good</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for drub that I've seen before include "Thrash" , "Beat repeatedly" , "Wipe floor with" , "Beat thoroughly" , "Beat conclusively in a competition or fight" .)