insert code via textbox?

Hi Guys,

I'm sure I've seen this before, but I can't find the thread...

I want to have the following in my detail page;

<?php echo $what_we_doRecord['additional_page_code'] ?>

where additional page code would be something like;
<?php include("_moduleAccommodation.php"); ?>

However, I think this is being stripped out? Is there a way I can get around this? Or another way of acheiving it?