Launder (4)
I believe the answer is:
wash
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">launder</span>' is the definition.<br/ ><span class="explanation-format__explanation">(washing is a kind of laundering)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for wash that I've seen before include "bath" , "Clean with water" , "Lave" , "Clean; thin coat of paint" , "Clean oneself" .)