Wiktionary
vb. (context of time English) To count down to zero (i.e. signaling the end (or start) of something).
Usage examples of "tick away".
Saffron minutes and green seconds tick away on the clocks on the walls.
Now, as she watched the second hand tick away, her palms began to sweat.
He pulled the door shut behind him, leaving Tristan alone to watch the interminable minutes of his wedding night tick away.
Sometimes he stopped and waited, letting the minutes tick away as he planned his next progression, gliding like a cloud's shadow cast upon the ground by the moon.
He listened to the windshield wipers tick away in their useless effort against the downpour.
Whenever Morse picked up his coat for the night and asked, as he often did, for 'a report in the morning', he could have had little idea of how long and difficult a job it was for his sergeant to get the sentences right in his mind, and then tick-tick away on the typewriter until late into the evening while his chief was sitting with his cronies in the local.
She hung on to that as she let the last seconds tick away, the last window of opportunity to stake him while the cuffs still held.