I believe you want $(this).find('.show-more')
but you can approach this a little less javascripty.
Here is what I'm thinking:
$('.news-items').on('click', '.show-more,.show-less', function () {
var $newsItem = $(this).closest('.news-item');
$newsItem.toggleClass('expanded');
});
Then control the less and more display from css.
.news-item {
border: 1px solid red;
margin-bottom: 10px;
}
.news-item.expanded {
height: 300px;
}
.show-less {
display: none;
}
.expanded .show-more {
display: none;
}
.expanded .show-less {
display: block;
}
Here is a small demo: http://jsbin.com/bidawudu/3/edit?html,js,output