Declines to see games of tennis (4)
I believe the answer is:
sets
'declines' is the definition.
(I've seen this in another clue)
'games of tennis' is the wordplay.
'games' becomes 'set' (I have seen 'games of tennis' mean 'set' so perhaps 'games' could also mean 'set').
'of tennis' becomes 's' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'set'+'s'='SETS'
'to see' acts as a link.
Can you help me to learn more?
(Other definitions for sets that I've seen before include "Plants" , "Solidifies" , "Coagulates" , "Classes" , "Scenery etc. of dramatic productions" .)