1)money for old rope：earning money very easily without any difficulty
容易赚钱；便宜事
2)next to nothing：next to=almost 几乎没有
next to no+noun： I have next to no bread to make sandwich with. 我几乎没面包来做三明治
3)pull the plug： to stop doing sth.结束; 终止业务
4)an ax to grind：另有所图；别有用心
5)not all it's cracked up to be：to not be as good as people have said 不像人们说的那样好
This software isn’t all it's cracked up to be.
6)fly under (the/someone's) radar： To go without being noticed, detected, or addressed
不被注意；不为人知地秘密行动
I like flying under the radar at school.
我喜欢在学校里默默无闻。
https://www.dictionary.com/games/quizzes/cuddle-up-a-cozy-quiz-on-fall-words-has-arrived
7)dredge up：=rake up 翻出(旧账)
8)crack down on：to take strong action镇压；制裁
9)tighten up：to become tighter加强；使紧密；拉紧
This valve has been tightening up from rust accumulating over the years.
经年的铁锈已经使阀门越来越紧。
10)To keep an ear to the ground： To listen or watch out for new information or trends.
例句：
Don't worry, I'll keep my ear to the ground and let you know what's happening as soon as possible.
11)buckle down：倾尽全力
12)riding for a fall：=cruisin for a brusin(cruisin for a brusin is the informal version ... this one is slightly more formal but neutral in formality)
to behave in a manner likely to cause one trouble or injury自讨苦吃；行动莽撞
13)a faint edge (over sb.)：微弱的优势 a little advantage
14)cordon sanitaire：防疫封锁线(借自法语)
15)on the blink：(=out of order)出故障主要针对机器或电子产品
My car is on the blink.
我的车有点儿毛病。
16)get sth. off the ground：get sth. started； to start doing well；to start succeeding 开始做某事；开始成功