What? No they don't. Clear verifies your ID when they enroll you but they do not maintain connections to every state's DMV nor the federal government's various ID issuing agencies. Once you are enrolled CLEAR is providing the required ID check via its bio-metric secured private database which uses information that it gathered when you enrolled and verified during that enrollment with various data sources including the physical ID check.

Anyone who thinks there is some well oiled massive IT back-end that connects the airlines and agencies and verifies everything at every step in real-time is living in a fantasy. There is one system, Secure Flight, that the airlines match against during check-in to determine if a passenger can be issued a boarding pass and, if so, what kind of boarding pass (SSSS, regular, or PreCheck). Once the boarding pass is issued any automated checking ends everything the TSA does lives in the barcode on the boarding pass (which is generally not verified until the airline boards the passenger). One of several vulnerabilities in the system is that one can easily make their own boarding pass at home and use their own (or someones or a fraudulent) ID to get past the checkpoint.