Is it just the order that's bothering you? That's easily fixed:
select
nvl(tree.tree_level,0) as tree_level,
tree.privilege,
p.privilege as child_privilege
from
test_acs_privileges p,
(select
level as tree_level,
privilege,
child_privilege
from
test_acs_privilege_hierarchy
connect by privilege = prior child_privilege
start with privilege in ('one_top_level', 'another_top_level')
) tree
where
tree.child_privilege(+) = p.privilege
order by tree_level,tree.privilege
