Operating rooms (8)
I believe the answer is:
theatres
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">operating rooms</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for theatres that I've seen before include "operational locations" , "Scenes of important events, like playhouses" , "Operating rooms" , "Set heart against performance spaces" , "Spaces for surgery and drama" .)