update_post_meta() whenever custom post type is updated

You’re right to use ‘save_post’ action hook.

Try this:

<?php

add_action('save_post', 'some_function');

function some_function($post_id)
{
        if(get_post_type($post_id) != "VA_LISTING_PTYPE")
        return;
    $meta_value = get_post_meta( $post_id, 'featured-cat', true );
    if($meta_value != 1)
        return;
    update_post_meta($post_id, 'website', '');
    update_post_meta($post_id, 'twitter', '');
    update_post_meta($post_id, 'facebook', '');
}

if you’re on WordPress 3.7 or higher, you can use it this way:

add_action('save_post_VA_LISTING_PTYPE', 'some_function');

function some_function($post_id)
{
    $meta_value = get_post_meta( $post_id, 'featured-cat', true );
    if($meta_value != 1)
        return;
    update_post_meta($post_id, 'website', '');
    update_post_meta($post_id, 'twitter', '');
    update_post_meta($post_id, 'facebook', '');
}

I hope it work with you.