Transparently thin (5)
I believe the answer is:
sheer
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">transparently thin</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 sheer that I've seen before include "Transparently thin - very steep" , "Downright - deviation" , "Very fine or vertical" , "Nothing other than" , "Steep; fine" .)