Well,
it is hard to tell from the pic, but if the soil is compact and hard, it needs something to loosen it up, like a stiff drink... or perhaps sand/peat/perlite or compost/organic material. Clay soils need sand, and sandy soils need clay! All soils can use good organic material, as it is used up in time and needs to be replenished. (Hence why farmers till in their crops.)
Soil should hold water AND yet be "light and airy", and drain well.
If you are uncertain, take a jar 1/2 full of soil, fill it with water, put the lid on and shake it up real well. Then let it settle and it should settle in layers. The smallest clay particles will usually separate from the larger sand, and the organic material also. This will give you a rough profile of what is in your soil.
Another easy thing to do, is to shove a shovel into it. If compact and hard, it is usually an indication of a lot of clay. (Sandy soils won't compact the same way.) Again, you can't go wrong adding more organic material.
If your soil grows normal garden plants well, it should work for Devil Claws.
That's about all I can suggest. I am sure there are others with more thoughts and suggestions concerning this.
Good luck.