I bit this particular bullet a couple of months ago. Turns out that a very cheap board like an Arduino Nano Every has a power voltage regulator (that will accept 6-21V supply) and a built-in clock, so you don't need to integrate anything.
(As it turned out, I wanted a more stable clock signal for timing purposes than the arduino clock, so I attached a 32.768kHz crystal to one of the inputs, and that also was very easy. I also attached a 4-digit 7-segment display, as there are enough I/O pins, a thermistor, several buttons/switches, and a stepper motor controller. It was easier than I thought. Give it a try.)
(As it turned out, I wanted a more stable clock signal for timing purposes than the arduino clock, so I attached a 32.768kHz crystal to one of the inputs, and that also was very easy. I also attached a 4-digit 7-segment display, as there are enough I/O pins, a thermistor, several buttons/switches, and a stepper motor controller. It was easier than I thought. Give it a try.)