aa7kn

In my 91 XJ, sometimes my clock goes off. Sometimes it goes off and on and when there is no clock, I notice that the horn won't blow. When the clock is normal, the horn works normal. My question is, are the clock and horn on the same circuit ? What could be causing the clock to go on and off ? I suppose the clock could be bad or have a bad connection, but why does it keep the horn from blowing? Thanks guys.