The responses gave me enough hints to get the job done. What I did was: -
- reinstalled Xcode Command Line Tools
- uninstalled old Homebrew
- installed new Homebrew (different default location)
- used Homebrew to reinstall git
- added brew and git folders to the path
- used Homebrew to install pyenv
- reinstalled python with pyenv
- used pyenv to set new version as the default
- used pyenv to delete the old version