Answer: surefire

AnswerCrossword Clue
SUREFIREBound to succeed
surefiresure to work; foolproof
surefiresure to meet expectations
SUREFIREImpossible to fail
SUREFIREGuaranteed to succeed
SUREFIRENever-failing
SUREFIREUnstoppable, as a plan
SUREFIREHighly dependable
SUREFIREPositive
SUREFIREGuaranteed
SUREFIRECan't miss
SUREFIRECertain to succeed.
SUREFIRECertain: Slang.
SUREFIRECertain to win: Colloq.
SUREFIREGuaranteed to work
SUREFIRELike guns that shoot every time?
SUREFIREFoolproof
SUREFIRECan't-miss