Stickler, of a sort

PEDANT

Think of someone who insists on precise grammar or trivial details, often to the annoyance of others—like a teacher marking every tiny error.

A "stickler" is someone who insists on strict rules or details, and "of a sort" hints at a more formal or precise term for that trait. The answer "PEDANT" fits because it describes a person who’s overly concerned with minor details or corrections, often in an annoying way. The clue plays on the idea of being fussy about language or rules, which is exactly what a pedant does.