"is there any other way without nesting?"
Not correctly, no. What is your problem with nesting? Nested queries are not inherently slower than unnested queries. In some cases, such as this, they are the only correct way to do the query. Even an analytic version of the Top N needs to be nested because:
SQL> SELECT object_name
2 FROM t
3 WHERE ROW_NUMBER() OVER (ORDER BY object_name DESC) < 11
WHERE ROW_NUMBER() OVER (ORDER BY object_name DESC) < 11
ERROR at line 3:
ORA-30483: window functions are not allowed here
It was not the fact that I had not read it but it had not made sense until I went over it 3 more times, rewrote it 10 more times that it now finally works and makes sense.
Not all of us learn by being called a plagueristic idiot. I am new to this and make mistakes. If that is the worst one then hoorah! (I'm just glad I am persistent)
I'll make more along the way. Til the next one :) Toodles and thanks. I have my answer.