Preprocess bean template, add template suggestions like view_mode

You can preprocess nodes and fields with hook_preprocess_field hook_preprocess_node, but when it comes to beans, you need to use different approach, hook_preprocess_bean doesn't exists. So to do this, you need to use this

function my_theme_process_entity(&$vars) {view_mode
  if ($vars['entity_type'] == 'bean') {
    if ($vars['bean']->type == 'YOUR_BEAN_TYPE') {
       $vars['theme_hook_suggestions'][] = 'bean__'  . $vars['bean']->type . '__' . $vars['#view_mode'];
    }
  }
}