Seguro TO_NUMBER()

De Oracle Database 12c Release 2 podrías usar TO_NUMBER con DEFAULT ... ON CONVERSION ERROR :

SELECT TO_NUMBER('*' DEFAULT 0 ON CONVERSION ERROR) AS "Value"
FROM DUAL;

O CAST :

SELECT CAST('*' AS NUMBER DEFAULT 0 ON CONVERSION ERROR) AS "Value"
FROM DUAL;

db<>demostración de violín