Island of north Wales (8)
I believe the answer is:
anglesey
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">island of north wales</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 anglesey that I've seen before include "British island known locally as Ynys Mon" , "Welsh island" , "Island off NW tip of Wales" , "Welsh county" , "part of North Wales" .)