fence in
1. To construct a fence around a particular area or thing. A noun or pronoun can be used between "fence" and "in." When our kids were little, we fenced our pool in so that they wouldn't be able to access it.
2. To restrict or limit someone. A noun or pronoun can be used between "fence" and "around." If you already signed a contract with them, I'm afraid you're fenced in.
fence an animal in
to enclose an animal and its area within a fence or barrier. We fenced the dog in to keep it at home. We had to fence in the dog.