Unexpected first sign of break -- game point following ace (6)
I believe the answer is:
abrupt
'unexpected' is the definition.
(thesaurus)
'first sign of break game point following ace' is the wordplay.
'first sign of break' becomes 'b' (I am not sure about this - if you are sure you should believe this answer much more).
'game' becomes 'ru' (rugby union).
'point' becomes 'pt'.
'following' is a charade indicator (letters next to each other).
'ace' becomes 'a'.
'b'+'ru'+'pt'='brupt'
'brupt' after 'a' is 'ABRUPT'.
Can you help me to learn more?
(Other definitions for abrupt that I've seen before include "Hurried or curt" , "Curt and short" , "Short in manner" , "Unexpected -- precipitous" , "Gruff" .)