Thanks Tom that works perfectly.
This is the code I ended up with for anyone with the same problem. Add as a code snippet and set a custom field on your post page with the name ‘wpsp_excerpt’ and the value as your custom excerpt and it will display for WP Show Posts. If nothing is set it will default to the excerpt length you have set.
if ( ! function_exists( 'wpsp_excerpt' ) ) {
function wpsp_excerpt( $excerpt_length )
{
global $post;
if ( get_post_meta( get_the_ID(), $key = 'wpsp_excerpt', $single = true ) ) {
$content = get_post_meta( get_the_ID(), $key = 'wpsp_excerpt', $single = true );
} else {
$content = wp_trim_words( get_the_content(), $excerpt_length, apply_filters( 'wpsp_ellipses', '...' ) );
}
// Strip shortcodes from our content
$content = strip_shortcodes( $content );
// Strip URLs from our excerpt (oembeds etc..)
$content = preg_replace( '~http(s)?://[^\s]*~i', '', $content );
// Return our content
echo $content;
}
}