What's between the players overall (3)
I believe the answer is:
net
I believe this is a double definition.
'what's between the players' is the first definition.
(tennis)
'overall' is the second definition.
(I've seen this in other clues)
(Other definitions for net that I've seen before include "Ultimate" , "Fish-catcher" , "Open weave fabric" , "Trap made from mesh" , "device to divide the court" .)