Remove p tag and then Add " "

functions.php

add_filter( 'the_content', 'wti_remove_autop_for_testimonial', 0 );
function wti_remove_autop_for_testimonial( $content )
{
     global $post;
     if ( $post->post_type == 'post' ){
          remove_filter('the_content', 'wpautop');
          $content = “ . $content. ”;
     }
     return $content;
}