Spoil or ruin (6)
I believe the answer is:
mangle
<span class="explanation-format__ClueExplanation">I believe this clue is a double definition.<br/ ><br/ >'<span class="explanation-format__original">spoil</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(I know that mangle is a type of blemish)</span><br/ ><br/ >'<span class="explanation-format__original">ruin</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ ></span>
(Other definitions for mangle that I've seen before include "Laundry squeezer" , "Mutilate - clothes wringer" , "Clothes-squeezer" , "Old-fashioned clothes dryer" , "rolling-press" .)