tldr; sometimes, crappy antivirus programs call ClickFix a virus. It isn't.
Because ClickFix needs to monitor clicks and decide which ones to allow through to the underlying system, sometimes poorly made antivirus software will flag it as malicious. This diagnosis is a false positive. As long as you downloaded the ClickFix.exe program through a secure connection to the main site or from the Github releases page then its integrity is ensured.
The full source of ClickFix is uploaded to this Github repository. If you would like to verify that the code behind the program is not malicious, read through the main script or compile it yourself with AutoHotKey.
If you are having trouble with ClickFix being blocked by antivirus software, add an exception for the ClickFix executable. If your software does not allow you to add exceptions, please consider replacing it with a better antivirus program (I personally recommend Avira or Avast - both have free versions).