Sphere of influence
I believe the answer is:
realm
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">sphere of influence</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for realm that I've seen before include "Knowledge base" , "the UK, perhaps" , "World" , "Kingdom, domain" , "Kingdom's" .)