I know, if a question is unclear, we should close it right-away, because otherwise people might interpret it in different ways and give inconsistent answers. But sometimes, before we can close it, the question gets and answer and the answer gets accepted.
This means that someone was able to understand the question and correctly address the problem of the OP, therefore the question was probably not so unclear as I had thought. Maybe it was just unclear to me.
Moreover, now that I can read the accepted answer, I understand what the OP wanted to ask, and the question is suddenly clear to me too (and presumably to everyone else that would like to answer it)
Closing the question would prevent additional answers to be posted, but it is unlikely that additional answers will come, because there is an accepted answer. In case they indeed come, they will be addressing the correct point, because the question has been clarified by the accepted answer.
So, should we close the question?
Some examples that made me think about this: What is z in this program or Life span of massive stars (the latter has been edited and clarified after being closed. I am referring to the question before the edit)