Select within a select in Oracle

Experts,

I  have seen the code before where partition by is used in an Oracle Query to get row_num and there is another query concatanated to it to get other columns within the table where row_num = 1. Can someone give me the syntax for this?  I  believe it looks something like this:

Select row_number() over (partition by member_id ORDER BY date_entered DESC) rownum FROM
 Select   member_id
           , claim
          , date_entered
FROM TABLEA
where rownum = 1;
quit;