Is 得弄 one word or two in 首先得弄清楚我们需要什么?
得 : got to / must / have to ABC must / need / should be
弄清楚 : ABC make clear; figure out


得 is read děi when it means must/have to/need to.

I would translate 首先得弄清楚我们需要什么。 as:

We first need to figure out what we need.