Use Basic English Please
"Clear Prop" is a useless phase for pilots to use anyway because:
1. airside personnel are usually very prop aware and tend not to dawdle around stationary or rotating propellers unless absolutely necessary. Therefore, any shouted warning is probably not really necessary for these folk.
2. in today's security conscious world very few non-aviation personnel are allowed airside and, even if they were, do we really believe that they would understand the operational impact of the shouted warning "clear PROP" (what's a prop fer chrissake? Something actors use or maybe its a piece of wood to jam a door open?).
If we have to shout warnings before starting, why don't we pilots simply use basic English and shout out "Stand (or Keep) Clear". At least then the average, non-aviation aware, airside blow-in who inadvertently gets too close to a prop might have some chance of avoiding disaster through being able to quickly comprehend the shouted warning.
I would strongly recommend all pilots change from shouting "Clear Prop" and use the phrase "Stand or Keep Clear" instead (or some other similarly appropriate plain English phrase).