Opposite of transparency (7)
I believe the answer is:
opacity
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">opposite of transparency</span>' is the definition.<br/ ><span class="explanation-format__explanation">('opacity' is the opposite to 'transparency')</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for opacity that I've seen before include "Lack of clarity" , "Unclear quality" , "Obscureness" , "Non-transparency" , "incomprehensible" .)