airmanship
A lot of what I see that is dressed up as airmanship these days is just folk lore ( IE dont lean below 3000 ft , turn your Cessna dead into wind before doing the runup ) but a loud shout of "clear prop" is an important safety item.
Apart from keeping people clear of the prop in these days when the dependants of a victim will rush to court on the flimsyest evidence not shouting "clear prop" may well be used to show that you did not take enough care to make sure the area was clear when starting the engine.