Try something like this:
$sotmArticle_query = new WP_Query(
array(
'post_type' => 'news',
'tax_query' => array(
array(
'taxonomy' => 'postCat',
'field' => 'slug',
'terms' => 'sotm'
)
),
'orderby' => 'date',
'order' => 'DESC',
'posts_per_page' => 1
)
);
if($sotmArticle_query->have_posts()){
while($sotmArticle_query->have_posts()){ $sotmArticle_query->the_post();
?>