This is without a doubt, better than anything that I could have written here.
Actions speak louder than words. Check out the main video on the following page (Randy Couture):http://www.totalvid.com/Mixed-Martial-Arts-Videos/Clinch-Take-Downs-from-the-Dominant-Position/
Watch that if you have the opportunity. 3.99 for a week download isn't bad considering what you're getting. Its at least a good look at the things that I consider to be of critical importance in the clinch.
There is probably no better instruction on the wrestling clinch on DVD. Further questions can be addressed here.
Thanks, good luck and good viewing all!