Excessively proper one, 5 letters
Overly prim and proper person, 5 letters
More like a schoolmarm, 8 letters
Excessively prim and proper, 6 letters
Fastidious to a fault, 6 letters
Overly prim and proper, 6 letters
Proper and then some, 6 letters
Straight-laced and then some, 6 letters
Too, too punctilious, 6 letters