If you clone via https you can do something like
git clone https://username@github.com/username/repository.git
This will prompt you for a password.
You can also directly provide a password by calling
git clone https://username:password@github.com/username/repository.git
But be aware that the password will be saved in .git/config and your bash history in that case which is not safe.
If you don’t like to enter the password every time you should consider cloning via ssh.