Noun clearance has 3 senses
  1. clearance - the distance by which one thing clears another; the space between them
    --1 is a kind of
    interval, separation
    Derived form: verb clear9
  2. headroom, headway, clearance - vertical space available to allow easy passage under something
    --2 is a kind of room, way, elbow room
  3. clearance - permission to proceed; "the plane was given clearance to land"
    --3 is a kind of
    license, permission, permit
    Derived form: verb clear4