(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?
*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.
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.”