establish (oneself, someone, or something) as (something)
To confirm oneself, someone, or something's role or reputation as being a certain thing or having a certain status. That merger established the company as the biggest on the East Coast. I think you need to establish yourself as a tough teacher early on so that the kids actually listen to you.
establish (someone or something) in (something)
To install someone or something in a particular place or role. I'm pretty sure his parents' wealth is what established him as a manager in the company right out of college.
establish someone or something as someone or something
to validate or confirm someone or something as someone or something. As soon as we establish her as a viable candidate, we will launch the publicity campaign. She established herself as an authority on rare books.
establish someone or something in something
to set someone or something up in something or some place; to install someone or something in something or some place. We established a restaurant in the middle of downtown. My uncle established me in the candy business.