UPDATE:
So off of the horn fuse came a single white wire, which 6" downstream was tied into: two green wires along with the original white wire . It looks like the previous owner may have done this, or maybe it's factory, but I'm not sure. Anyway, after disconnecting the wires and trying them individually to find which was causing the short circuit, I found out that the white wire went to the hazard switch on the dash.
After jumping 12v to the hazard switch, thereby bypassing the white wire all together, smoke began coming from the trouble spot. The culprit was a bare wire in the stereo wiring which was shorting out on a bracket.
Thanks for everyone's help. The clock still doesn't work, but I'll address that later.
The moral of the story for anyone searching is that the #5 fuse for a seemingly benign circuit such as horn/hazard/clock, is actually tied into many things which may present itself as no spark at the coil, and prevent your car from starting.
Cheers.