Definition of Excess Clause
In insurance policy, such clause provides for insurer’s liability up to limits of policy covering excess loss only after exhaustion of other valid insurance. Underground Const. Co., Inc. v. Pacific Indem. Co., 49 Cal.App.3d 62, 122 Cal.Rptr. 330, 333.
That's the definition of Excess Clause in Black's Law Dictionary 6th Edition. Courtesy of Cekhukum.com.