The best way to handle a false positive is to let the people at ClamAV who maintain the signatures know about it. Go to
http://cgi.clamav.net/sendvirus.cgi on the web to upload the file(s) and tell them. They will update the signature(s) if necessary to exclude false positives.
I always like to check out the file(s) at
http://www.virustotal.com/ with VirusTotal first. VT will check files for free against 30 antivirus programs. If a couple of other antiviruses besides Clam spot a virus, it's probably not a false positive.
Regards,