certain or definite 确定无疑；板上钉钉 The referee refused to award a nailed-on penalty. 裁判拒绝判罚。 - be nailed on for something
He thought he was nailed on for the England job. 他以为自己在英格兰工作上被钉上钉子。
(in betting ) believed to be very likely to succeed （打赌）胜算很大的 a nailed-on bet 胜算很大的赌局