So, I need to echo the URL of a custom field from the last post published in a certain post type and with a particular taxonomy.

This code so far works OK, but even that numberposts = 1, $imagecurrent will contain the image URL from all the posts matching the conditions, not only the last one.

<?php 
    $args = array(
        'posts_per_page'=> 1,
        'post_type'     => 'exhibition',
        'tax_query' => array(
        array(
          'taxonomy' => 'exhibitions',
          'field' => 'id',
          'terms' => 720, // Where term_id of Term 1 is "1".
        )),
    );

    $the_query = new WP_Query( $args );

?>
<?php if( $the_query->have_posts() ): ?>
    <?php while( $the_query->have_posts() ) : $the_query->the_post(); ?>
        <?php echo $imagecurrent = get_field('exhibition_menu_image');
    ?>
    <?php endwhile; ?>
<?php endif; ?>

<?php wp_reset_query(); ?>

What am I missing?

EDIT

I have included the code from the solution (posts_per_page), but it's still spitting out the URL from all posts, not only the last one.