How to reset specific form elements
You can attach the reset function in this way:

function submission_list($form, &amp;$form_state){
  $form = array();
  $form['name'] = array(
    '#title' =&gt; 'Name',
    '#type' =&gt; 'textfield',
  );
  $form['surname'] = array(
    '#title' =&gt; 'Surname',
    '#type' =&gt; 'textfield',
  );
  $form['actions'] = array(
    '#type' =&gt; 'actions',
    'submit' =&gt; array(
      '#type' =&gt; 'submit',
      '#value' =&gt; t('Submit'),
      '#attributes' =&gt; array(
        'class' =&gt; array('my-submit-button-class')
      ),
      '#submit' =&gt; array('your_submit_function')
    ),
    'reset' =&gt; array(
      '#type' =&gt; 'submit',
      '#attributes' =&gt; array('class' =&gt; array('my-reset-button-class')),
      '#value' =&gt; t('Reset form'),
      '#submit' =&gt; array('submission_list_reset')
    )   
  );
  return $form;
}

function submission_list_reset($form, &amp;$form_state) {
  $form_state['values']['name'] = '';
  $form_state['values']['surname'] = '';
}

function your_submit_function($form, &amp;$form_state) {
  drupal_set_message('The form has been submitted');
}


But please consider to use ajax callback for this reset function, it would be better do not reloading the page only because of resetting. More info - Ajax forms in Drupal 7