Large structure (7)
I believe the answer is:
edifice
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">large structure</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 edifice that I've seen before include "Monument" , "Impressive building" , "'Large, imposing building (7)'" , "Grand building" , "Construction" .)