Grand National venue (7)
I believe the answer is:
aintree
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">grand national venue</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 aintree that I've seen before include "Venue of the Grand National race" , "Home of the Grand National" , "National racecourse" , "Liverpool's racecourse" , "place for horse racing" .)