Naevus (9)
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">naevus</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for birthmark that I've seen before include "Skin pigmentation" , "Naevus" , "Blemish on the skin" .)
(Other definitions for mole that I've seen before include "Spy; blemish" , "Amount of substance" , "Spy - one that burrows" , "Breakwater; naevus" , "digger" .)