Games of tennis still end occasionally being fixed (7)
I believe the answer is:
settled
'being fixed' is the definition.
(thesaurus)
'games of tennis still end occasionally' is the wordplay.
'games of tennis' becomes 'set' (I've seen this before).
'occasionally' indicates alternate letters (letters taken at regular intervals or occasions).
'still'+'end'='stillend'
The alternating letters of 'stillend' are 'tled'.
'set'+'tled'='SETTLED'
(Other definitions for settled that I've seen before include "Took up residence" , "came to agreement" , "Agreed; sorted" , "Established" , "Sank or came to rest" .)