I have a question that has nearly a final answer, but it could use some rephrasing and updating. What is the idiom for handling this situation? Should attempt to edit the answer and then accept that, or should I add my own answer and accept that?
As noted in the comments, above, try commenting on the answer first. If you don't get a response in a "reasonable" amount of time, feel free to edit the answer and accept it.
We fully encourage editing here, but it is of course always best to attempt direct communication first whenever practical.
If you are not comfortable with the idea of your contributions being collaboratively edited by other trusted users, this may not be the site for you.