Commercial building (6,5)
I believe the answer is:
office block
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">commercial 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 office block that I've seen before include "Commercial building" , "commercial property" , "Business building" , "Large work building" .)