Foe of the Sioux (6)
I believe the answer is:
pawnee
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">foe of the sioux</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 pawnee that I've seen before include "one living in America" , "N American native" , "North American Indian - one taking a pledge" .)