StringFormat or converter for binding dates?

Hi,

I have a datetime that is being bound to a listbox and I only want to show the time portion of it.

I've tried

<TextBlock Text ="{ Binding TimeFeedStart, StringFormat=t }" Margin ="3,0,0,0"/>

But this throws an error.

Am I correct in thinking that StringFormat doesn't work on binding in windows apps?

If this is the case, can someone please help me with a converter that I can use to get the output I require?

Any help is gratefully received.

Thanks