Programmatically clear/reset cache for a specified Node
Drupal 8+
\Drupal::entityTypeManager()->getStorage('node')->resetCache([$nid]);
Drupal 7
entity_get_controller('node')->resetCache([$nid]);
\Drupal::entityTypeManager()->getStorage('node')->resetCache([$nid]);
entity_get_controller('node')->resetCache([$nid]);