Do you have to give way to a car that is making a U-turn when starting from the roadside?

Explanation

Starting from the roadside places the driver outside the established traffic stream, so every road user already on the carriageway must be allowed to pass. That duty includes the oncoming car crossing the driver's path; whether its leftward manoeuvre is a turn or a full reversal does not remove its priority, and the driver's own indicator confers none.