echo ‘<span class=”excerpt”>’;
the_excerpt();
echo ‘</span>;

No need to use the html entities.
This will work

add_action( ‘woocommerce_after_shop_loop_item_title’, ‘lk_woocommerce_product_excerpt’, 35, 2);
if (!function_exists(‘lk_woocommerce_product_excerpt’))
{ function lk_woocommerce_product_excerpt()
{ echo ‘<span class=”excerpt”>’; the_excerpt(); echo ‘</span>’ } }

I can’t tell if it is syntactically correct, but it crashes.

” & lt; “span class=”& quot ” ;excerpt”& amp;” ” quot”;” & gt; ”

My Short description test shown here

“& lt ;”/span” &gt ;”
but as mentioned the ‘right’ code crashes

EDIT Sorry the code pasted in as working not as ampersand gt