Third-party stakeholders (e.g., suppliers, customers, partners) understand roles & responsibilities. PROTECT (PR) Function, Awareness and Training (PR.AT) Category. Outcome in the Framework Core of Version 1.0; reworded in Version 1.1 as: "Third-party stakeholders (e.g., suppliers, customers, partners) understand their roles and responsibilities".
This control maps to 2 controls across 1 other frameworks. If you already hold one of them, the evidence you collected for it is the starting point here rather than new work.
NIST-CSF-PR.AT-01 Personnel are provided with awareness and training so that they possess the knowledge and skills to perform general tasks with cybersecurity risks in mind
NIST-CSF-PR.AT-02 Individuals in specialized roles are provided with awareness and training so that they possess the knowledge and skills to perform relevant tasks with cybersecurity risks in mind