Assuming it is 'live', if you can insulate the bare end of the wire in the car it'll be safe until you can make a proper fix. Unfortunately, to reach the wiring you'll have to have the B-pillar trim off and maybe carpets up - the wiring loom won't have any slack in it. Please be careful! Car batteries have enough amps to melt metal, let alone set a fire. Disconnect the battery before you start work. Sorry, but I'm about the leave the country until Thursday... I hope others can assist. Vanbursta could be your man!