Break in Irish game, point behind (6)
I believe the answer is:
irrupt
'break in' is the definition.
(I've seen this before)
'irish game point behind' is the wordplay.
'irish' becomes 'ir' (abbreviation).
'game' becomes 'ru' (rugby union).
'point' becomes 'pt'.
'behind' means one lot of letters go next to another.
'ir'+'ru'+'pt'='IRRUPT'
(Other definitions for irrupt that I've seen before include "Enter forcibly and suddenly" , "Enter forcibly or violently" , "Break, rush, in" .)