Not dirty (5)
I believe the answer is:
clean
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">not dirty</span>' is the definition.<br/ ><span class="explanation-format__explanation">('clean' is the opposite to 'dirty')</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for clean that I've seen before include "Wash" , "Absolute - pure" , "Sterile" , "Untainted" , "Pure; well-defined" .)