How To Make an Oscillator For AM Radio with Arduino UNO R3?

I was trying to make an Oscillator for AM radio with PWM from Arduino.
Is there any way to oscillate like a 1MHz quartz crystal oscillator?
And what should be the code for that?

It is possible to program a timer to toggle an output pin at around 1 MHz. Study the MCU data sheet, timer section, for the details.

What does PWM have to do with your project?

PWM produces a block wave (basically lots of different frequencies superimposed onto one another), normal AM radio requires a pure sine wave. So for that reason it won't work.
You'll have to get a real radio transmitter - preferably one that's licensed for use in your locality (so also using an unregulated frequency, and not producing harmonics).

Is this oscillator for direct a conversion receiver or to produce an IF. If the latter what is the Intermediate Frequency you want. Is this oscillator meant to tune the radio?