(American football) In the AFL, a warning given with one minute to go before the end of a half, after which special rules apply, eg, stoppage of the game clock after very first down.

(card games) In card playing, to accidentally reveal one's cards or hand. / (figuratively) To inadvertently reveal any secret, particularly a secret that puts one at an advantage or disadvantage.

(idiomatic) A recording artist known for only one hit song, especially after failing at subsequent attempts at success.

To behave in a manner appropriate to one's age. / (imperative, originally US) To behave in a mature manner; to avoid being childish.

In a pleasing state or form.

(idiomatic) Close behind; pursuing or following closely.

(bingo) eight

(informal) Legitimate; honest; upright.

Used other than figuratively or idiomatically: see let, on. / (idiomatic) to reveal or indicate, especially unintentionally or against one's wishes

(idiomatic) barely; closely; by a narrow margin; with nothing to spare.