afterburner (beta 14) will let you lower it to 685. Real value as shown using GPU-Z sensors tab.
Then start your cgminer with -gpu-memclock 685
I'm running cgminer at 1200/685, see my signature for details.
Not with the latest AMD drivers it doesn't.
Version 8.96 (Feb 14) pretty much breaks AB completely.
In fact, i had to uninstall it to get my card to even run a stock clocks.
Hopefully Unwinder will fix it soon, but it's in AMD's lap now.