Ready for some tennis? (3)
I believe the answer is:
set
I believe this clue is a double definition.
'ready' is the first definition.
(set can mean ready or prepared)
'some tennis?' is the second definition.
'for' is the link.
(Other definitions for set that I've seen before include "What the Sun regularly does" , "Gel; group" , "Put down the tennis group" , "Become solid like jelly" , "Customary < scenery < a TV < series" .)