wordpress list only one catory posts code example

Example: show all posts from category

<?php
    $args = array( 'category' => 7, 'post_type' =>  'post' ); 
    $postslist = get_posts( $args );    
    foreach ($postslist as $post) :  setup_postdata($post); 
    ?>  
    <h2><a href="<?php the_permalink(); ?>"><?php the_title(); ?></a></h2> 
    <?php the_excerpt(); ?>  
    <?php endforeach; ?>