I think you can apply techniques from any other program to make a snare sound clappy in Reason. Find some good samples, EQ, and make use of the transient shaper and compressor within Kong drum designer.
One thing I noticed: don't resample your snare + clap and hipass it to put it on the sides, it will just cancel eachother out, even when you add some fx. The snare will obliviate. It's for obvious reasons, but just telling you it really cancels out..
I did however just mention the technique to your succes. Take a snare, layer 2 claps on the sides, and don't make them too prominent and that will give it this slight extra punch. You could also have some white noise layered, that's usual in dubstep tunes or electro.. Another method might be trying to accomplish this in mastering, where you can boost or cut EQ at the mid or the sides, (at least in iZotope Ozone) and then you bring up the highs around 2-3k a bit on the sides. There are just so many more options to take. But I would start with layering a snare with a clap and EQing about for a while, to see where problems occur.. I do therefore agree with the above, throw ur clap or snare, or both through some KONG fx's (if you don't like kong as do I you can simply route your samples into the input and output of KONG so you just use it for FX) and fuck about until you find something reasonable.
If all fails, get an oldskool dnb samplepack, they are usually full of snareclaps..