There is a site that I go to on Chrome, but now it's blocking it, saying it's malicious. Is there a way to keep the security, but allow this one site?
Check the URL with VirusTotal, the odds are is that it's a false-positive. https://www.virustotal.com/
You can use some proxy to open that webpage, it bypasses malware protection, like https://whoer.net/webproxy Well, it works for me.
Since this is a phishing detection, the server hosting the site you're visiting has likely been compromised to host a phishing page on a random URL. Browse at your own risk.