Safety risks are a relative thing. Clamd is running the ClamAV engine on files and directories.
Where are you getting the figure that it's taking up that much memory? Linux memory management can be misleading; sometimes it is just telling you what's allocated, but not actually resident, and Linux is usually pretty good about juggling applications out when they're not active. You'll probably see that a lot more memory is used in caching than this application is taking up.
Personally, I'd not kill it. It is a relatively simple way to add another layer of "Peace of Mind", and if it's not impacting your system performance significantly then let Linux do its thing with managing memory. If you're hitting a lot of swap or disk thrashing, then see about trimming processes, but really at that point you might need to consider upping memory instead.
The flip side to ask is how much it will hurt you if the site is hacked and you don't realize it. Time to restore from backup, time to untangle any blacklists, do you have clients or others that depend on access to this system that will be affected, reputation, etc...is it really worth it to you to kill the malware scanner in that case? Is it worth investing in more memory instead of killing the application, when weighed against the alternative? That should give you the answer you need.
My answer if you asked me in person this question is that yes, there's a security risk in that this gives you one more layer of protection and another vector of discovering potential exploit attempts. Is it a huge security risk, I wouldn't think so, as long as you're careful. But it does increase your risk, just as not wearing your seatbelt increases your risk of injury or death in a car accident but it doesn't mean that you're doomed the next time you don't do it. Risk is up to you to quantify in your own situation.