Break in game, neat time to intervene (7)
I believe the answer is:
rupture
'break in' is the definition.
(thesaurus)
'game neat time to intervene' is the wordplay.
'game' becomes 'RU' (rugby union).
'neat' becomes 'pure' (both can mean undiluted).
'time' becomes 't' (abbreviation).
'to intervene' means one lot of letters goes inside another (intervene can mean to enter into).
'pure' enclosing 't' is 'pture'.
'ru'+'pture'='RUPTURE'
(Other definitions for rupture that I've seen before include "Burst suddenly" , "Bursting" , "Ecstasy" , "Breach, severance" , "State of being torn or burst open" .)