clean up: 1.扫除,清扫eg：to give the house a good clean up 给房子来一次彻底的扫除.
2.【美俚】赚的一大笔钱
clear up：1.说明,解释,解答 eg：to clear up a mystery 解开谜团
2.整理,收拾,完成 eg：Don't expect me to clear up after you(tidy your things)all the time.不要老是指望我替你收拾东西.
3.好转,结束 eg:I hope the weather clears up before Sunday.我希望星期日前天气会转晴.