I want to pinpoint it here:
1. A USA citizenship is a minimum prerequisite for a security clearance.
2. Security clearance has a few levels (about four).
3. If you don't have a USA citizenship, you don't have security clearance. Just answer "No".
4. Security clearance takes about eight months to over a year to complete. In the course of the processing, you have lots of chances to talk with police office and your company's security officer. If you don't even understand the question about security clearance, I bet you don't have it. Just answer "No".