Longest river in Scotland (3)
I believe the answer is:
tay
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">longest river in scotland</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 tay that I've seen before include "Longest Scottish river" , "Wicklow lake" , "Scottish loch" , "Scottish river in Katayama?" , "Dundee's river" .)