I right click on the clock, go to properties, and play with the settings. 

Under "clock options", there are several options, but nothing exactly like what i want, and when i change the drop down to "custom" i am presented with a text entry field.

with no way of knowing what to input here, i cannot customize this option effectively. some help in the dialog would be very helpful. 

i managed to bruteforce some of the syntax, i ended up finding what i wanted:

%l:%M %p

Some help/documentation would be greatly appreciated!