clock

1 clock /ˈklɑːk/ noun
plural clocks
1 clock
/ˈklɑːk/
noun
plural clocks
Britannica Dictionary definition of CLOCK
1 
[count] : a device that shows what time it is and that is usually placed in a room or attached to a wall
— often used before another noun
— compare watch; see also alarm clock, atomic clock, biological clock, body clock, cuckoo clock, grandfather clock
2 
the clock : a clock that is used in sports and that shows how much time remains for a particular part of a game
◊ In U.S. English, to eat up the clock or run out the clock or kill the clock is to keep control of the ball or puck near the end of a game so that your opponent will not have a chance to score.
— see also shot clock
3 
the clock : time clock
4 
the clock chiefly British, informal : a device that shows how far a vehicle has traveled : odometer

against the clock

1 
: in order to do or finish something before a particular time
2 
◊ If a race is against the clock, the time of each racer is measured and the racer with the fastest time wins.

around the clock

also round the clock
: throughout the entire day and night : every hour of the day

beat the clock

: to do or finish something quickly before a particular time

put/turn back the clock

also put/turn the clock back
: to return to a condition that existed in the past
2 clock /ˈklɑːk/ verb
clocks; clocked; clocking
2 clock
/ˈklɑːk/
verb
clocks; clocked; clocking
Britannica Dictionary definition of CLOCK
1 
[+ object]
a  : to measure the amount of time it takes for (a person) to do something or for (something) to be completed — usually + at
b  : to finish a race in (an amount of time)
2 
a  [+ object] : to measure or show (the speed of something) with a measuring device
b  [no object] : to have a particular speed or to continue for a particular amount of time — + in
3 
[+ object] informal : to hit (someone or something) very hard
4 
[+ object] British, informal : to look at or notice (someone or something)

clock in/on

[phrasal verb] chiefly British
: to record on a special card the time that you start working

clock off/out

[phrasal verb] chiefly British
: to record on a special card the time that you stop working

clock up

[phrasal verb]
clock up (something) chiefly British
: to gain or reach (a particular number or amount)