You use the same slug clubs to register your custom post type and in rewrite when you register opposition taxonomy.
Change rewrite parameter in register_taxonomy()
'rewrite' => array(
'slug' => 'clubs/opposition',
'with_front' => false
),
The recognizable address will be clubs/opposition/{some-term-name} and will display posts from custom category.
However, the clubs/opposition address will still not work without additional code.