I am not sure how you could alert based on one specific query causing 80% CPU use because SQL Server abstracts a lot of that but you could get a list of all the queries and their CPU use for analysis when the server goes above 80% CPU use. You could do this by setting up a WMI Alert in SQL Agent that would run a job when CPU reached 80% on the server. The job could capture all running queries. Be careful with this kind of approach though, it can make bad times worse depending on how aggressive your job is at pulling information from the server.