using (var context = new SampleEntities())
			{
				var contacts = from c in context.Contacts
							   where c.FirstName == "Robert"
							   let foo = new
							   {
								   ContactName = new { c.Title, c.LastName, c.FirstName },
								   c.Addresses
							   }
							   orderby foo.ContactName.LastName
							   select foo;
				
				foreach (var contact in contacts)
				{
					var name = contact.ContactName;
					Console.WriteLine("{0} {1} {2}: # Addresses {3}",
						name.Title.Trim(), name.FirstName.Trim(),
						name.LastName.Trim(), contact.Addresses.Count());
				}
			}

Notice that the property name declared (foo) is used later in the query for the ORDERBY operator and SELECT statement.

Anonymous types as properties in LINQ

C#