What is "up to the hub"

Hub \Hub\ (h[u^]b), n. [See 1st Hob.]

1. The central part, usually cylindrical, of a wheel; the nave. See Illust. of Axle box.

2. The hilt of a weapon.
   --Halliwell.

3. A rough protuberance or projecting obstruction; as, a hub in the road. [U.S.] See Hubby.

4. A goal or mark at which quoits, etc., are cast.

5. (Diesinking) A hardened, engraved steel punch for impressing a device upon a die, used in coining, etc.

6. A screw hob. See Hob, 3.

7. A block for scotching a wheel.

8. The central location within which activities tend to concentrate, or from which activities radiate outward; a focus of activity.

9. Hence: (Aeronautics) A large airport used as a central transfer station for an airline, permitting economic air transportation between remote locations by directing travellers through the hub, often changing planes at the hub, and thus keeping the seat occupancy rate on the airplanes high. The hub together with the feeder lines from remote locations constitute the so-called

   hub and spoke system of commercial air passenger transportation. A commercial airline may have more than one such hub.

10. The city of Boston, Massachusetts referred to locally by the nickname The Hub.

    Hub plank (Highway Bridges), a horizontal guard plank along a truss at the height of a wagon-wheel hub.

    Up to the hub, as far as possible in embarrassment or difficulty, or in business, like a wheel sunk in mire; deeply involved. [Colloq.]

adv. As far as possible in embarrassment or difficulty, or in business; deeply involved.