'A new brush sweeps clean' means that someone with a new perspective can make great changes. However, the full version is 'a new brush sweeps clean, but an old brush knows the corners', which warns that experience is also a valuable thing. Sometimes 'broom' is used instead of 'brush'.
Ifs and Buts is a term used to describe the reasons people give for not wanting to do something. To show that you don't wish to accept any excuses, you can tell somebody that you wish to hear no ifs or buts Here IF & BUT have become nouns
(UK) 'A nod's as good as a wink' is a way of saying you have understood something that someone has said, even though it was not said directly. The full phrase (sometimes used in the UK ) is 'a nod's as good as a wink to a blind horse'.
This indicates that the person described is unaware of his or her good fortune or is unaware of how difficult day to day life was before he/she was born. Typical usage: 'Kids today don't know they are born'.
To end on a muted note - most likely in a situation where one would have expected a more spectacular finish. This expression was coined by T.S. Elliot in his 1925 poem, The Hollow Men, which ends: This is the way the world ends This is the way the world ends This is the way the world ends Not with a bang but a whimper.
This means that something is worthless and dates back to when someone would travel around the countryside repairing things such as a kitchen pot with a hole in it. He was called a 'tinker'. His dam was used to stop the flow of soldering material being used to close the hole. Of course his 'trade' is passé, thus his dam is worth nothing.