Posição bem explicada nestas descrições de funções. Mais do que um mero defensor, é uma função de responsabilidade/coordenação da implementação de causas, normalmente de natureza social/ambiental, dentro de empresas e organizações, incluindo ONG.

OECD Watch is recruiting an Advocacy Lead to oversee the development and implementation of a new campaign aimed at improving access to remedy for...

https://www.business-humanrights.org/en/advocacy-lead

This is an exciting new role to lead the development and
delivery of our Foundation-wide advocacy approach.
The postholder will lead advocacy efforts around the
potential for Learning through Play to contribute to ECD
and educational outcomes by giving children the skills they
need to thrive. This will be a challenging and evolving role,
which will begin by helping to shape our overall approach
to advocacy, then helping to develop a portfolio of
investments and internal capabilities to deliver against that
approach.

https://jobs.smartrecruiters.com/BusinessTransformationGroup...

Job Description
The Advocacy Lead is responsible for managing communications and outreach in support of the Light Rail Infrastructure Project in Maryland. This position serves as a public information liaison and a communication link between the Light Rail Infrastructure Project and its stakeholders, and will require developing and maintaining effective working relationships with government and public officials, community partners and project managers. The Advocacy Manager develops and administers public awareness and education through outreach programs; defines strategies and proactively responds to informational needs; and provides project communications and other key information at stakeholder meetings, community outreach and public information sessions.

Pelos textos que a Ana apresentou, me parece que a função desta pessoa é a promoção "da causa" atraves de articulação.