Association football (6)
I believe the answer is:
soccer
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">association football</span>' is the definition.<br/ ><span class="explanation-format__explanation">(synonyms)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for soccer that I've seen before include "American football?" , "Football for Americans?" , "Association football" , "popular game" , "Roy Keane's game" .)