Pack das Ganze in eine Klammer:

select * from (
Select *
From BESTELLP
Start With B1BNR02 = 7635561
Connect By Prior B1BNR01 = B1BNR02
) Hugo
where BINR02 = 0


oder

Select *
From BESTELLP
Start With B1BNR02 = 7635561
Connect By Prior B1BNR01 = B1BNR02
Order By BINR02
Fetch First Row Only