Tennis term (5,5)
(Other definitions for match point that I've seen before include "may secure victory in court" , "Decisive moment in game" , "One serve away from victory" , "a single ace away from victory" , "that may bring victory" .)
'tennis term' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for ace that I've seen before include "'wicked'!" , "Tennis serve that the receiver can't reach" , "Girl" , "Outstanding" , "SERVE?] that's non-returnable" .)