The icing in the sim is far overdone, so yep it can happen in clear skies.
If you get icing, you can also enable Developer mode and go to the options, there is a slider for visual icing which you can pull to the left to remove it.
But as long as the sim thinks you’re in icing conditions, it will build up again.
Let’s hope we can soon disable icing entirely since that’s not simulated realistically anyway.