Such a question might be too broad.
If you are unable to explain a solution fully, it means you are missing something required to complete the answer. Assuming it is not your own training or experience, the question may be missing a piece of information, or one aspect of it might be too vague. Providing an answer would be far too verbose, or could boil down to "pick something."
Let us consult the "too broad" close reason:
There are either too many possible answers, or good answers would be
too long for this format. Please add details to narrow down the answer
set or to isolate an issue that can be answered in a few paragraphs.
The proper thing to do in this case is to ask for clarification in a comment:
I tried answering your question and came up with some good points, but
this one aspect is giving me trouble: do you mind expanding on this a
little bit to help nail down the scope or provide additional
It may be acceptable to provide the answer anyway and edit it later: this depends on if your answer is complete enough to be useful as-is. If you are missing something optional, or provide a big enough push in the right direction, then go ahead and answer.
The key to think of is to ask yourself if I were someone else, would I upvote or downvote the answer as-is without the additional clarification? I hope I do not need to explain whether to post or to wait depending on the outcome of that self-question.
Please do keep in mind that Stack Exchange is about living content that is owned by the community: every day, users go back and edit years-old questions and answers as the underlying information evolves. Several times per week I edit old answers to update broken links, add notes about evolving technology (e.g. "back in Java 5 this was how it was done, now we have some new-fangled Java 8 feature that makes it easier"), and more. There is nothing wrong with leaving a valid answer then going back and improving it later. They key is valid answer: do not write a half-assed answer and expect to go back and edit it without a few downvotes and comments to take care of.