Definition of "clearance"

clearance

/ˈklɪəɹən(t)s/

noun
countable and uncountable, plural clearances
1. The act of clearing or something (such as a space) cleared.
2. The distance between two moving objects, especially between parts of a machine
3. The height or width of a tunnel, bridge or other passage, or the distance between a vehicle and the walls or roof of such passage; a gap, headroom.
  Quotations
  Piggybacking introduced severe clearance problems for many railroads.
  1960 November, David Morgan, “""Piggyback"—U.S. success story”, in Trains Illustrated, page 684
4. A permission for a vehicle to proceed, or for a person to travel.
5. A permission to have access to sensitive or secret documents or other information.
  Quotations
  In a thread called “Calm Before the Storm”, and in subsequent posts, Q established his legend as a government insider with top security clearance who knew the truth about a secret struggle for power involving Donald Trump, the “deep state”, Robert Mueller, the Clintons, pedophile rings, and other stuff.
  2018 July 31, Julia Carrie Wong, “What is QAnon? Explaining the bizarre rightwing conspiracy theory”, in The Guardian‎
6. A permission to use something, usually intellectual property, that is legally, but not otherwise, protected.
7. (retail) A sale of merchandise, especially at significantly reduced prices, usually in order to make room for new merchandise or updated versions of the same merchandise.
8. (banking, finance) The settlement of transactions involving securities or means of payment such as checks by means of a clearing house.
9. (medicine) The removal of harmful substances from the blood; renal clearance.
10. (sports, billiards, snooker, pool) The act of potting all the remaining balls on a table at one visit.
11. (soccer) The act of kicking a ball away from the goal one is defending.
  Quotations
  Bolton were then just inches from taking the lead, but the dangerous-looking Taylor drilled just wide after picking up a loose ball following Jose Bosingwa's poor attempted clearance.
  2010 December 29, Chris Whyatt, “Chelsea 1 - 0 Bolton”, in BBC‎
12. (chess) Removal of pieces from a rank, file or diagonal so that a bishop, rook or queen is free to move along it.
13. Clear or net profit.
  Quotations
  There can, I believe, be no doubt of this, that sugar can be made better and cheaper in large quantities than in small. But the clearance, sir; that is the question. How would this affect the clearance? The sugar manufacturer would want his profit.
  1859, Anthony Trollope, The West Indies and the Spanish Main
14. (Australian rules football) The first disposal in a chain that leaves the area of a stoppage, or a disposal that leaves the area of a stoppage itself.
15. (Australian rules football) The act of leaving the area of a stoppage.