I've seen many lego clock escapements on the internet but many use large gears which I didn't have. Also there are very little tutorials. This is a slightly modified version of a design by ben van de waal (his youtube channel is: https://www.youtube.com/channel/UCfl5b1Fplm3y1HUboj0InFg) This is a simple design that doesn't need much adjustment to work.
Step 1: The Mechanism
Just follow the pictures. Some of it is in a bit of a random order but it should be easy enough.
Step 2: The Pendulum
The pendulum consists of 11 axles that are 10 blocks long, with two tyres on the end. A shorter pendulum swings faster. For an accurate clock, it needs tick every second. Connect it to the bottom of the base you made just now.
Step 3: The Weight
Tie some string to the wheel (There should be a hole inside that you can tie it on to) and add a weight. I used a 1/2 oz metal weight but you can use anything that weighs roughly the same amount, including lego.
Step 4: Just About Done
Everything is pretty much complete. You'll want to add some lego to the back so it doesn't topple over. You could even make a housing for it. Wind up the string (you have to disconnect the swinging bar on the front first) then put it somewhere high and give the pendulum a nudge. It should start ticking away. If it doesn't work, you may need to adjust the positions of the lego that connects to the bar. They can be moved horizontally, you want them to hit the arms as it spins around. Mine runs for 2 minutes. It would run longer if it had more than 4 pins, this is just a simple demonstration of how an escapement works.
Any problems or ideas, let me know in the comments.