Pepys' Diary: Monday 14 January 1660/61

neat
At this time primarily (in this context) 'simple and elegant,' the OED's definition 7:

7 Characterized by elegance of form or arrangement, with freedom from all unnecessary additions or embellishments; of agreeable but simple appearance; nicely made or proportioned.In early use the handsomeness of the thing appears to be the more prominent idea.