Hi,
If you have canonical URLs in your products and you have the "force canonical URLs on listings" setting activated in your HikaShop configuration, no coding is needed.
You can just add
#hikashop_product_top_part
to the canonical URL in each product.
Otherwise, you can edit the file "listing_img_title" of the view "product" via the menu Display>Views and change the line:
$link = hikashop_contentLink('product&task=show&cid=' . (int)$this->row->product_id . '&name=' . $this->row->alias . $this->itemid . $this->category_pathway, $this->row);
to:
$link = hikashop_contentLink('product&task=show&cid=' . (int)$this->row->product_id . '&name=' . $this->row->alias . $this->itemid . $this->category_pathway, $this->row).'#hikashop_product_top_part';