Protecting reset pin from overvoltage
I suggest using diodes to clamp the voltage. In the configuration bellow, the diodes will clamp as soon as the Input signal goes over 5V+Vf.

What this means is that the maximum voltage you will have at the reset port will be typically 5.7V. Excess voltage will be blocked by the diodes.

This solution needs you to have a 5V source on your design that can provide the clamping reference.







simulate this circuit &ndash; Schematic created using CircuitLab

You might also want to look into TVS diodes, you have more info on that here. These diodes will clamp to their rated voltage without the need of a power supply to fix that value.