Wanted to do this aswell in 4.2 and after some failures found this works:
<p class="descr">{$product.descr}</p>
I got it to display under the SKU code at the top of the item by adding it below:
{if $config.Appearance.display_productcode_in_list eq "Y" && $product.productcode}
<div class="sku">{$lng.lbl_sku}: {$product.productcode|escape}</div>
{/if}
Hope that helps others on 4.2