Less contaminated (5)
I believe the answer is:
purer
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">less contaminated</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 purer that I've seen before include "Less immoral" , "More chaste" , "cleaner" , "more clean" , "Less adulterated" .)