1
general::
A small, modest, or obscure place, as in My new apartment is just a hole in the wall, or Believe it or not, that little hole in the wall is a great restaurant. This graphic term is often used disparagingly. [First half of 1800s]
American Heritage Idioms
2
general::
Phrase(s): a hole in the wall
Fig. a tiny shop, room, etc., not much wider than its doorway. • I went into this little hole in the wall where they had the nicest little gifts. • His office is just a hole in the wall.
McGrawhill's American Idioms And Phrasal Verbs