To create a view in a stored procedure, you need to do this in dynamic SQL (especially since the view itself cannot accept a variable).
DECLARE @sql NVARCHAR(MAX);
SET @sql = 'CREATE VIEW dbo.tblList
AS
SELECT ItemOrder, DisplayVal,
SomeAlias = DATEADD(DAY, DaysDue, ''' + CONVERT(CHAR(8), @PDate, 112)
+ ''') FROM dbo.tblLine WHERE ID = 1;';
EXEC sp_executesql @sql;
, , dbo.tblList, . , , , , " ".