display post excerpt with post subtitle

add_filter( 'jnews_module_excerpt', 'excerpt_by_subtitle', 99, 4 );


function excerpt_by_subtitle( $excerpt, $post_id, $excerpt_length, $excerpt_more ) {

    $subtitle = wp_kses( get_post_meta( $post_id, 'post_subtitle', true ), wp_kses_allowed_html() );
    if ( ! empty( $subtitle ) ) {
        $excerpt = $subtitle;
    }
    return $excerpt;
}