I notice that with the specific question, it was actually the OP who figured out how to do the problem and therefore provided the one answer currently seen.
As a general rule it is fine to ask an answer writer for more details or clarifications. This can be a good alternative to posting a new question.
Please note that some people only ask for hints on problems. And some people will only post hints as answers. This is completely fine. So you might not receive a more detailed answer.
If a question only asks for a hint, I would discourage you from posting a full answer.
If you come across a question with a partial answer and you would like to see a more detailed fuller answer, you are free to post this as a new question. Make a reference to the question with the partial answer and explain what further thoughts you have.
In summary for this specific situation I would
- post a comment asking for more details.
- wait a day or two and if you don't receive any response, then post a new question explaining why the hint given wasn't enough for you to solve the problem.