Sufficed (6)
I believe the answer is:
served
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">sufficed</span>' is the definition.<br/ ><span class="explanation-format__explanation">(serving is a kind of sufficing)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for served that I've seen before include "In tennis, smacked ball into play (6)" , "Dished up" , "In tennis, put the ball in play, or attended to customers" , "Waited upon" , "Started a game of tennis" .)