The obtrusive site, opens regularly, which I am not interested in

No. Force Quit Safari and open holding the Shift Key down. That should fix the issue.

If you want to take a deep dive, then you could go into Safari's Preferences, Select Privacy, click on Manage Website Data, Search for "bit.ly" and delete those cookies.

Good as new.

If that did not work. Go back into Safari preferences, privacy, manager websites and delete all. Also check extensions in preferences and delete or turn off any extension. You can turn them back on one at a time and try it. if one of them causes the redirect delete it. Also check under General for correct home page and search for correct search engine. If you can get to google search, download Malwarebytes free and run it. You could have adware causing this. You can also type Malwarebytes.com on the top panel in Safari to go to the download site.