Well Anne, I am going to jump in again since I see you are looking at this thread.
The original post brought up a specific point, and it is possible that the clip on their particular Sebenza was out of adjustment.
My comment about CRK clips in general comes from lots of experience clip carring knives from a number of manufacturers and makers.
It seems to me that the following factors are more likely to produce a reliable clip carry:
1. Position clip high on the knife. As the clip moves lower on the body of the knife, the more weight and bulk are left up above the clip, increasing "walk" and "rise". (Yes, there is a trade off with accessibility here).
2. Center the clip on the body of the knife. This balances the rotational forces on the clip. Eccentric clip positioning increases problematic rotation.
3. Make certain that there is significant contact area between the clip and the clipping surface. Wide and long clips increase friction between the knife body and the clothing. YMMV depending on friction of knife surface (toothy G-10 is the best) and the clothing you are wearing. Narrow, short clips with minimal contact area (like Sebenza clips) are the least favorable.
4. Very light and very heavy knife bodies seem to provide the most reliable clipping. The light knife simply won't rotate or rise up too much. The very heavy knife is self-ballasting. The clip design needs to take this into account.
My favorite clips/folder combos (as examples):
CRK Mnandi (solves all of the problems that the Sebenza and Small Sebenza clip designs have)
Spyderco Chinook
Spyderco Native G-10
Benchmade Stryker
Benchmade 690 Series
Allen Elishewitz Matrix series clips
Microtech LCC
There are many more, I am sure, these are off the top of my sleep-deprived memory (that's my 14 month old getting up in middle of night).
The absolute worst clip designs of all time(short list):
MOD Hornet
CRKT S-2
Feel free to criticize my very subjective points. However, most of my points are simple physics issues. When I carry a Sebbie, I try NOT to use the clips. I just take the clips off and carry them in a slip sheath. If I happen to be wearing jeans, they slip just fine into the change pocket.
I like Sebenza folding knives very much, particularly the Classic designs. I just think the clips are not particularly sucessful designs.