neat as a pin

(as) neat as a pin

Tidy; clean; in good or neat order. I expected Danny's student apartment to be a total mess, but it was as neat as a pin when we arrived! I expect you to leave this kitchen neat as a pin when you finish for the night, understand?
See also: neat, pin
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.

*neat as a pin

Cliché neat and orderly. (*Also: as ~.) Brad is such a good housekeeper; his apartment is always as neat as a pin. Joanne certainly is well-organized. Her desk is neat as a pin.
See also: neat, pin
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs. © 2002 by The McGraw-Hill Companies, Inc.

neat as a pin

Trim, orderly. This term dates from the late eighteenth century and appeared in print in several works by John Wolcot (who used the pseudonym Peter Pindar), as “neat as a new pin.”
See also: neat, pin
The Dictionary of Clichés by Christine Ammer Copyright © 2013 by Christine Ammer
See also:
References in classic literature ?
They followed the Yellow Hen into the house, which Aunt Em declared was neat as a pin. They could not sit down, because all Billina's chairs were roosting-poles made of silver; so they had to stand while the hen fussily showed them her treasures.
She was a plump, black-eyed little woman, neat as a pin, but with a rather tired and care-worn face that looked as if it should have been rosy and jolly.
She takes swig BEER WE GO: Rihanna holds bottle NEAT AS A PIN: Rihanna's ear-rings