Last October, Clear Channel, the owner of eight radio stations in the Denver area, merged with AMFM, controller of six local signals. Because of FCC regulations, Clear Channel was then forced to divest the half-dozen AMFM properties -- and the purchaser of three of them was Infinity Broadcasting, the most prominent challenger to Clear Channel nationwide. The results of these deals won't be known for a while yet, but they're likely to lead to a titanic scrap unlike any that Colorado radio observers have ever seen. Let the battle begin.