Being within a building (6)
I believe the answer is:
indoor
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">being within a 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 indoor that I've seen before include "Situated under cover" , "For inside use" , "covered" , "Under a roof, like some sports" , "Sport like snooker, darts or badminton" .)