Ans:

<?xml version="1.0" encoding="utf-8"?>
<s:Application xmlns:fx="http://ns.adobe.com/mxml/2009" 
   xmlns:s="library://ns.adobe.com/flex/spark" 
   xmlns:mx="library://ns.adobe.com/flex/mx" 
   minWidth="955" minHeight="600">
<fx:Script>
<![CDATA[
import mx.collections.ArrayCollection;
[Bindable]                
private var myDP:ArrayCollection = new ArrayCollection([
{Name:"Bikrant", City:"Delhi"},
{Name:"Brijesh", City:"Bombay"},
{Name:"Ravi", City:"Kanpur"},
{Name:"Avanish", City:"Chennai"}
]);               
]]>
</fx:Script>
<s:Panel title="MX inline item renderers and item editors Example" 
 width="316" height="260" 
 chromeColor="#555555" color="#CCCCCC" backgroundColor="#000000">
<mx:DataGrid id="myDG" dataProvider="{myDP}" 
 variableRowHeight="true" 
 editable="true"  x="52" y="31"
 chromeColor="#C2A5A5" 
 color="#000000">
<mx:columns>
<mx:DataGridColumn dataField="Name" headerText="Name"/>
<mx:DataGridColumn dataField="City" 
   editorDataField="selectedItem" 
   headerText="City">
<mx:itemEditor>
<fx:Component>
<mx:ComboBox >
<mx:dataProvider>
<fx:String>Delhi</fx:String>
<fx:String>Bombay</fx:String>
<fx:String>Kanpur</fx:String>
<fx:String>Chennai</fx:String>
<fx:String>Lucknow</fx:String>
</mx:dataProvider>
</mx:ComboBox>
</fx:Component>
</mx:itemEditor>
</mx:DataGridColumn>
</mx:columns>
</mx:DataGrid> 
</s:Panel>
</s:Application>