Ajit Kumar Satpathy

These must be in function.php in the theme for the plugin to work for thumbnail and excerpt:
add_theme_support( ‘post-thumbnails’ );
set_post_thumbnail_size( form_option(‘thumbnail_size_w&&echo=false’), form_option(‘thumbnail_size_h&&echo=false’), true );
function custom_excerpt_length( $length ) { 
 return 20; 
} 
add_filter( ‘excerpt_length’, ‘custom_excerpt_length’, 999 ); 
function custom_excerpt_more( $more ) { 
 return ”; 
} 
add_filter( ‘excerpt_more’, ‘custom_excerpt_more’ );
You’ll also need to add thumbnails to the posts you want visible in the list.
After that, all you need to do is to add the hook [getcatlist 1] (where 1 is a categoy id) to your post.

Category Thumbnail Excerpt

Lists a category with thumbnails,title,excerpt with a read more link

Mark Howells-Mead

Adds a new column to the WordPress admin post list view, containing a preview of the post’s featured image (where available).
<h3>Hooks</h3>
Developers can use the <code>mhm-list-postthumbnail/exclude_posttype</code> filter to exclude the post thumbnail column from certain post types as required. The filter accepts and returns an array.

Add post thumbnail to wp-admin list view

Adds a new column to the WordPress admin post list view, containing a preview of the post's featured image (where available).

Category Thumbnail Excerpt vs Add post thumbnail to wp-admin list view