Strategic clarity is a product of strategic thinking, rather than strategic planing. It comes from being clear about who you are, what values you bring to the company or the project, and what the outcome should be.
I visualize strategic clarity as being able to walk into any situation and know what you must do. This means more than having a mission statement, or organizational values. It is more like having a story that provides a way to define who you are and why you do the things you do.