sure·fire 
/ˈʃɚˈfajɚ, Brit ˈʃɔ:ˈfajə/ adjective
always used before a noun /ˈʃɚˈfajɚ, Brit ˈʃɔ:ˈfajə/ adjective informal : certain not to fail : sure to be successful
▪ surefire solutions ▪ The movie is a surefire hit/success with teenagers. ▪ There is no surefire way to predict the outcome.
▪ surefire solutions ▪ The movie is a surefire hit/success with teenagers. ▪ There is no surefire way to predict the outcome.
