DNS question

[robbo007]

Hello everyone,
I've had to move a clients webpage temporary off my server to another server and have changed the following DNS record so that www works:

www IN A 8x.9x.xxx.xxx

This works fine for http://www.clientsdomain.com but not for http://clientsdomain.com

How can I can I change the web DNS for http://myclientsdomain.com without affecting the other services like mail etc. Is this possible?

Thanks,
Rob