$re = '/(.*?)<div.*div>(.*)/s';
$str = '"<img width="300" src="https://www.dvrgv.org/PhotosArticles/2017-07-25-VeloTaxi.jpg" alt="Manu dans le vélo-taxi, Brigitte aux commandes" /><br />
<P>En juillet 2017, </P>
<div class="powerpress_player" id="powerpress_player_9779"><!--[if lt IE 9]><script>document.createElement(\'audio\');</script><![endif]-->
<audio class="wp-audio-shortcode" id="audio-1097-1" preload="none" style="width: 100%;" controls="controls"><source type="audio/mpeg" src="https://www.dvrgv.org/_Reportages/2017-07-26-BrigiteVeloTaxi.mp3?_=1" /><a href="https://www.dvrgv.org/_Reportages/2017-07-26-BrigiteVeloTaxi.mp3">https://www.dvrgv.org/_Reportages/2017-07-26-BrigiteVeloTaxi.mp3</a></audio></div>dddf"
';
$subst = "\1\2";
$result = preg_replace($re, $subst, $str);
echo "The result of the substitution is ".$result;
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php