Anton Essential,
<!DOCTYPE HTML>
<html>
<head>
<title>Untitled</title>
<meta charset="utf-8">
<style type="text/css">
.minus, .sub-menu {
display: none;
}
</style>
<script src="http://code.jquery.com/jquery-1.9.1.js"></script>
<script>
$(function() {
$('ul li').on('click',function(event) {
event.stopPropagation();
var elements = $('ul:first, .plus:first, .minus:first', $(this));
elements.toggle()
});
});
</script>
</head>
<body>
<div class='some-class'>
<ul id='accordion'>
<li>
<p>Нажмите тут</p>
<span class='plus'>+</span>
<span class='minus'>-</span>
<ul class='sub-menu'>
<li>
<p>Нажмите тут</p>
<span class='plus'>+</span>
<span class='minus'>-</span>
<ul class='sub-menu'>
<li>123</li>
</ul>
</li>
</ul>
</li>
</ul>
</div>
</body>
</html>