Island with Trinidad (6)
I believe the answer is:
tobago
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">island with trinidad</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 tobago that I've seen before include "Trinidad companion island" , "Section of WI" , "island location" , "Caribbean island" , "Island paired with Trinidad" .)