Starts a tennis match (6)
I believe the answer is:
serves
'starts a tennis match' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for serves that I've seen before include "What a waiter does" , "Puts the tennis ball in play" , "Strokes that puts the ball in play" , "Puts the ball in play on court" .)