Meaning of CLEARANCE in English
clear ‧ ance /ˈklɪərəns $ ˈklɪr-/ BrE AmE noun
[ Word Family: noun : ↑ clarity , ↑ clearance , ↑ clearing , ↑ clarification , ↑ clearness ; verb : ↑ clear , ↑ clarify ; adverb : ↑ clear , ↑ clearly ; adjective : ↑ clear ≠ ↑ unclear ]
1 . [uncountable and countable] the process of getting official permission or approval for something:
She’ll race if she gets medical clearance from her doctor.
Morris did not have a security clearance.
2 . [uncountable and countable] official permission for a plane to take off or land
The pilot requested clearance for an emergency landing.
3 . [uncountable and countable] the removal of unwanted things from a place:
the clearance of minefields
snow/land/slum etc clearance
flooding caused by forest clearance
4 . [uncountable and countable] the amount of space around one object that is needed for it to avoid touching another object:
There was less than a foot’s clearance between the ship’s sides and the wharf.
5 . [uncountable and countable] a process by which a cheque goes from one bank to another
6 . [countable] an occasion when a player in a game such as football kicks the ball away from his or her ↑ goal
Longman Dictionary of Contemporary English. Longman - Словарь современного английского языка. 2012