What is syntax for selector in CSS for next element?

The > is a child selector. So if your HTML looks like this:

<h1 class="hc-reform">
    title
    <p>stuff here</p>
</h1>

... then that's your ticket.

But if your HTML looks like this:

<h1 class="hc-reform">
    title
</h1>
<p>stuff here</p>

Then you want the adjacent selector:

h1.hc-reform + p{
     clear:both;
}

You can use the sibling selector ~:

h1.hc-reform ~ p{
     clear:both;
}

This selects all the p elements that come after .hc-reform, not just the first one.

no > is a child selector.

the one you want is +

so try h1.hc-reform + p

browser support isn't great

This is called the adjacent sibling selector, and it is represented by a plus sign...

h1.hc-reform + p {
  clear:both;
}

Note: this is not supported in IE6 or older.