Use but not in a widget

Why you don’t create new sidebar called “Top category”

Goto wp-content/themes/your_theme/

1/ Open functions.php and paste this code

register_sidebar( array(
		'name' => __( 'Top Category', 'default' ),
		'before_widget' => '',
		'after_widget' => "",
		'before_title' => '<h3 class="widget-title">',
		'after_title' => '</h3>',
	) );

2/ Open category files (usually it is archive.php) and goto the place you want to show this widget and paste this code

<?php if ( ! dynamic_sidebar( 'Top Category' ) ) : ?>

<?php endif;?>

3/ Goto Widget and drag widget “jcarousel-post-slider” to Top Category.

Done!