Transparent gemstone (8)
I believe the answer is:
amethyst
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">transparent gemstone</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 amethyst that I've seen before include "Semiprecious stone of violet or purple quartz" , "rock" , "Purple quartz, used as a gemstone" , "Bluish-violet 3" , "Violet gemstone" .)