How do you give employees clear strategic direction but also inspire flexibility and risk taking?

The one best answer is to create and broadcast a “strategic principle”—a pithy, memorable distillation of strategy that guides employees as it empowers them.

Allow me to differ here ...

Your question is talking about employees in general ... and the answer should apply to all employees and not a special category of them (managers, supervisors, leaders, executives, ...)  ... right ??If so, my opinion is that employees need to stick to their job descriptions and execute their roles and carry their responsibilities according to what is stated in their job descriptions...   They (generally speaking) do not need to be flexible and they do not need to take risks   ... otherwise, the organization may become in a mess !! On another aspect, it is my view that the strategic direction is not something for work-level (low levels in the organization structure).  Yes, the need to be aware of the strategic direction, but these employees perform their duties in the operational (and possibly tactical) level, not at the strategic level. Having said that, the key to the puzzle is something I have done for several clients already. It is called "operational alignment with the strateguc direction"  ..  In this service (may take3-6 months depending on organization size and diversity), we do not align the employees directly to the corporate strategic diretion, but through functional/departmental intermediate step 

1. Align the departments/functions/units to the corporate strategic direction
2. Align the employees to the department/function level strategic direction whisch is already aligned to the corporate strategic direction 

This work involves functional/deparmental/business unit management, HR, corporate development, office of strategy management, corporate goveranance, ... etc .. etc