A person who heads up a particular movement or group is its standard-bearer. The President of your French club is the ideal standard-bearer, with her beret and that perfect accent.
A standard-bearer leads an organization, but also represents it. If a news story says that a new member of Congress is a standard-bearer for young conservatives, that means she speaks for many politicians who share those beliefs and is seen as a leader among them. This meaning comes from the original definition, "a soldier carrying (or bearing) the flag of a specific military unit or state."