Sufficed (6)
I believe the answer is:
served
'sufficed' is the definition.
(serving is a kind of sufficing)
This is all the clue.
(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" .)