If you want to show only want one item, you can use the Generic Content control, drag it on page, and select an item from the shared-items list.
There is one more way, which is introduced in Sitefinity 3.5. You can use the FilterExpression field (it is located just above the SummarySettings), and enter the following as an expression:
|Name = "contentName" AND Category = "YourCategory"
I hope this is helpful.
the Telerik team
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