How to use div class between the shortcode variable?

It’s a bit difficult to understand or provide an accurate answer as we don’t know what the shortcode is executing. Is it stripping html or any other parsing?

If this is your own code, then you could add it in the function the shortcode is calling.

If its not you could try a couple options:

1: (adding the div directly into the shortcode call)

<?php echo  do_shortcode( '[shortcode]<div>'.$var.'</div>[/shortcode]'), ; ?>

2: add it to the $var first:

<?php  
  $dvar="<div class="own">".$var.'</div>';
  echo do_shortcode('[shortcode]'.$dvar.'[/shortcode]');
?>

Again, the ideal solution would be to see that function and then put the div directly in before the shortcode is executed.