First thing to do is to figure out how much is drawing on the battery. If a new battery went flat in a week, it looks like a fairly large draw. One quick thing to do is disconnect the + lead on the battery and remove all the fuses and put a test lamp between the + cable and the post of the battery, see if the light comes on and how bright it is. Removing the fuses eliminates a lot of items. If your light stays on, start checking the alt ( again disconnect and see if the light goes out ) If the light does not come on with all the fuses out, put one fuse in at a time and see if the test light comes on. This is just a matter of trial and error. Ign switch, lights, wipers , all of these things could cause a draw. Remove the interior , trunk and hood bulbs to make sure that it isn't one of those. Get a good wiring diagram Good luck
Clock probably won't be enough to draw the battery down, that would take a least a month to do. Do you have a sound system in the car? a lot of times . they continue to draw after the key is off. Don't leave the key in the ignition ( some do when the car is in a secured garage )