There are several meanings/ utilizations of "有个交代” 1. As is in your example: ... 我对你有个交代 which means accomplish your unfinished will; 2. "在这个问题上 希望政府对人民有个交代“ which means be able to explain it or straighten things out; 3."领导要出差 临走前对工作有个交代” which means make task arrangements in advance; In traditional Chinese culture, people believe that there is an afterlife. But people are not able to move on to the afterlife if they have unfinished last wishes. Their souls are still entangled in this world. If "有个交代” is related to finished last will, in a way it means "let go".

your translation: 我最终对你有了一个交代。 'I finally achieved closure for you your translation is good, if you want to convey the whole sentence in English. but using "closure" represent "交代" here, which is like a metaphor and could not explain "交代" very well. so I think "交代" should be clarified, and maybe, if I do so, it will be helpful for you to translate and memorize the meaning in the feature In the following context, the two "交代" has two different meanings : 1."交代(1)" - verb 2. "交代(2)" - noun, In my opinion, the most important thing to your question is the meaning of "交代(2)-noun" which is derived from "交代(1)- verb" (hand over) 你让我照顾你的孩子。=你"交代(1)"我一個任務 = you hand over a task/mission to me, (here "交代(1)" means "hand over"-verb ) 我把他抚养成人。 = ....part of the mission 我最终对你有了一个"交代(2)"。= (I have accomplished my mission you hand over to me), so I finally also could have something/perfect report which I can "hand over" (back) to you . here "交代(2)" means "something/perfect report" which I can "hand over" back to the person who assign the mission to me after achieving the mission. here "交代(2)" means "something" which can be replaced by "(good) perfect report/reply/response" Hope you can find something helpful.

有个交代 is a very Chinese and has no equivalent meaning in English. I have checked many bilingual sentences with 有个交代, and find that people translate it in different ways according to the situation. e.g: 我想你得对交给你保管的每一分钱作一个交代。 I think you will have to account for every penny of the money that was entrusted to you. 我要对我们的生活有个交代。 I have to believe I got some kind of say over our lives. 柯克承认，这种方法没有扭转公众情绪，但至少我们对他们有个交代。 While Kirk acknowledged that this approach 'hasn't turned the public sentiment, but at least we have a good story to tell. ' I think, the original meaning of it is that when we finish doing something, we will give a final report or explanation to people involved. This thing is called 交代. If we didn't do our duty very well, it will be hard for us to do this, right? So in my opinion, the meaning of 有个交代 is like have something nice to say, and implies that we have done our duty.

我这样做也是对你有个交代，对咱儿子有个交代。（你和儿子都还活着） 可见，“交代”与死不死没什么关系。一个人死不瞑目，主要是两个原因，一是觉得自己死的冤枉，一是自己有非常大的遗憾，比如有没完成的心愿，有放不下的亲人之类。这和“交代”没有直接关系，只不过是“愿意”没实现中的一种情况罢了。 看大家解释，感觉英语也许没有这样的文化，那就很难让他们明白“交代”的真正含义。比如解释成“accomplish your unfinished will”　“完成了你最后的愿意”，不一定就是给他了一个交代。因为他可能完全没有想要你给他一个交代。可见“交代”其实是站在完成者的角度讲的，那怕对方说：请你给我一个交代。这个“交代”依然是由做的一方要做出、完成的事。

In this case, I think it's more like "let somebody down." 我要讓你受良好教育，才能對你死去的爸爸有個交代。 Something like "I have to do my best to offer you the best education, so I won't let your father down"