select /*+ no_merge(a) */  * from (
        select dept_no,dept_name,level lev ,'parent' relType from department
          start with dept_no=10 connect by dept_no=prior parent_dept_no
        union  
        select dept_no,dept_name,level lev,'child' relType  from department 
          start with dept_no=10  connect by parent_dept_no=prior dept_no
      ) a  where a.lev=1 and a.relType='parent'  
  

for example, data could be this:
  dept_no   parent_dept_no  dept_name
  10        5               d1
  5         1               d2
  20        10              d3
  1                         d_top
  I hope the sql could return collection like this:
    DEPT_NO DEPT_NAME                   LEV RELTYPE
  ---------- -------------------- ---------- -------
        10 d1                            1 parent

  but,oracle returns two rows:
    DEPT_NO DEPT_NAME                   LEV RELTYPE
  ---------- -------------------- ---------- -------
        10 d1                            1 child
        10 d1                            1 parent