Sports teams (5)
I believe the answer is:
sides
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">sports teams</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 sides that I've seen before include "Lines" , "Opposing factions or facets" , "Borders?" , "parties" , "Takes the part of someone in a dispute" .)