One who carries a flag, especially at a ceremony.(noun)
One who openly promotes an idea or value and becomes symbolic for it.(noun)
Wiktionary.org : Text is available under the Creative Commons Attribution-ShareAlike License
Use "flag-bearer" in a sentence
"We were admired and respected as the flag-bearer of a free and democratic nation."
"Downturn creates new hurdles for Olympic site's flag-bearer"
"Which is the whole point of the confederate flag question in the first place … a flag can symbolize certain things to certain people without these things being adopted or advocated by the flag-bearer in their use of the flag for other purposes."