You can use multiple fields (e.g. Answer1, Explanation1, etc.) or use custom syntax like answer1 [[explanation one]] then change it with JavaScript like this:
<div id=t>{{Front}}</div>
<script>
var e = document.getElementById('t');
e.innerHTML = "<details><summary>" + e.innerHTML.replaceAll("[[", "</summary><p>").replaceAll("]]", "</p></details>").replaceAll("<br>", "<br><details><summary>");
</script>