1 the removing of sth that is old or not wanted 清除: The shop is having a clearance sale (= selling things cheaply in order to get rid of them). 这家商店正在举行清仓大廉卖。

2 the distance between an object and something that is passing under or beside it, for example a ship or vehicle 净空（一物从另一物下面或旁边经过时，两者间的空隙）: There was not enough clearance for the bus to pass under the bridge safely. 这座桥下的净空不足以让那辆公共汽车安全通过。

3 official permission for sb/sth to do sth 正式批准: She was given clearance to work at the nuclear research establishment. 她被正式批准在核子研究机关工作。