What is the correct tablespoon measure for yeast?

A tablespoon measures quantity, not weight. So a tablespoon of yeast will not be the same weight as a tablespoon of butter, or sugar. In the case of this recipe, a level tablespoon of yeast would weigh roughly 8.5-9 grams. A rounded tablespoon would weigh in a bit more, perhaps around 11 grams. Less yeast to start with will mean the dough requires longer to double, but the end product will not be much different. However, since the recipe does call for 11 grams, that's what will be most likely to give the results in the time frame given.