Irish Gaelic (4)
I believe the answer is:
erse
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">irish gaelic</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 erse that I've seen before include "Name sometimes given to languages of the Celts in Ireland and Scotland" , "Irish Gaelic language" , "Old Gaelic for the seer" , "Kind of Gaelic for seer" , "Old language spoken by strange seer" .)