I want to implement this circuit:

the voltage divider is fed from a 12V source, and is switched via Q7. Is this safe to use for the 5v MCU or what is the best practice in this situation.

I want it switched to save power when not needed so will apply it to other sensors which are 5v so that wont be a problem.

 

When the MOSFET is off, the 12V is connected to the MCU via the 10k. The MCU likely has protection diodes on the input so it may be OK, but check the MCU spec. In any case current will still be flowing from the 12V via 10k and diode to the 5V supply.
You really need to do this with a high side switch.

 

You really need to do this with a high side switch.

thought this be the case