Circular domed building (7)
I believe the answer is:
rotunda
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">circular domed building</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 rotunda that I've seen before include "Italian Pantheon, for instance" , "Round building or hall" , "Round domed building" , "Round domed room" , "circular construction" .)