May birthstone (7)
I believe the answer is:
emerald
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">may birthstone</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for emerald that I've seen before include "Ireland is often called The .......Isle" , "On of the Greens" , "Precious gemstone" , "Green gemstone" , "Gem; type of moth" .)