A ball game played to the letter (5)
I believe the answer is:
omega
'the letter' is the definition.
(omega is a kind of letter)
'a ball game played' is the wordplay.
'a ball' becomes 'o' (O looks like a ball).
'played' indicates an anagram.
'game' with letters rearranged gives 'mega'.
'o'+'mega'='OMEGA'
'to' is the link.
(Other definitions for omega that I've seen before include "Traditional story" , "letter from abroad" , "End of sequence" , "end of series" , "Consummation" .)