It looks like Clam is having trouble pulling signature updates, can you check the following? This might just do the trick :-)
1. Check server DNS to ensure at least ONE outside DNS server is available. Personally I recommend 220.127.116.11 (Google DNS.)
2. Check SmarterMail DNS addresses to ensure ONE outside DNS server is available.
3. If there is a proxy connection between the server and the internet, you may want to bypass the proxy connection for outbound connections to Clam's update server.
Most of the time these issues are DNS related! After updating the server addresses, and verifying connectivity, restart the SM service and attempt update again.
Kyle Kerst Cameron Solutions LLC www.cameron-solutions.com