well, if you're confident about the consistency of the feed:
$newsfeedpos=strpos($bigstring, "Newsfeed");
$mystring=substr($bigstring, $newsfeedpos);
$morenewspos=strpos($mystring, "more news click here");
$mystring=substr($mystring,0,$morenewspos);
Of course, if you think about it, you could combine all that code into one statement, couldn't you?
Or you could use preg_replace and capture just the text you want, but that would take 2 statements.