standard-bearer

standard-bearer
n
(a) person who carries a standard(4) 旗手; 掌旗者.
(b) (fig 比喻) prominent leader in a cause, esp a political one 领导人; 先行者; （尤指政治上的）旗手
    a standard-bearer for women's rights 争取妇女权利的旗手.

牛津英汉双解词典