control-shop-excerpt-length.php

function custom_flatsome_woocommerce_shop_loop_excerpt(){
    if(!flatsome_option('short_description_in_grid')) return; ?>
    <p class="box-excerpt is-small">
         <?php /*echo get_the_excerpt();*/ ?>
         <?php echo wp_trim_words( get_the_excerpt(), 10); ?>

    </p>
    <?php
}
add_action('flatsome_product_box_after', 'custom_flatsome_woocommerce_shop_loop_excerpt', 21);

add_action('init', function(){  
remove_action('flatsome_product_box_after', 'flatsome_woocommerce_shop_loop_excerpt', 20);	
});