一字之師 yī zì zhī shī

DEFINITIONS

  1. one who can correct a misread or misspelt character and thus be your master

CHARACTERS

一 yī one; a, an; alone
字 zì letter, character, word
之 zhī marks preceding phrase as modifier of following phrase; it, him her, them; go to
師 shī teacher, master, specialist; multitude, troops