You probably have a mix of things to clean up, soot, burnt resin, burnt solder mask, leakage of electrolyte from the capacitor etc. I would start by removing the component and then with a good scrub using an old toothbrush and some high purity solvent/ Isopropanol. Then see where you're at with the burnt board. You may need to cut some of it away, if you're lucky, just the surface layer with something like a dremel if it's really bad underneath. More important though is that the component can still be mounted in some fashion and that the tracks going to each pin are either kept intact or, as I mentioned earlier, bridged with some short lengths of insulated wire to the next closest component's solder pad. Use a good quality replacement capacitor, something branded from Panasonic, Dublier, Rubycon etc. Stay away from the cheap chinese capacitors...