A green gemstone (7)
I believe the answer is:
emerald
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">a green gemstone</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for emerald that I've seen before include "...re medal? (Anag)" , "Small size of type, in printing" , "Highly-valued variety of beryl" , "On of the Greens" , "Precious gemstone" .)