Tennis match part (3)
I believe the answer is:
set
'tennis match part' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for set that I've seen before include "What the Sun regularly does" , "Customary < scenery < a TV < series" , "group usually found together" , "Gel; group" , "Group; unchanging" .)