ORA-00932 Wjem getting the sub-string

[SQLpower]

Hello,

So shortly I am receiving an SQL Error: ORA-00932: inconsistent datatypes: expected NUMBER got OE.CUST_ADDRESS_TYP
00932. 00000 - "inconsistent datatypes: expected %s got %s" when I am trying to retrieve a part of a string data.

SELECT dbms_lob.SUBSTR(cus.cust_address, 0, INSTR(cus.cust_address, ',')-1) AS output
  FROM oe.customers cus;

So basically that's my statement.

The data looks like : OE.CUST_ADDRESS_TYP('322 E Michigan St','53202','Milwaukee','WI','US')

And I only want to display the city, which in this case would be Milwaukee.

However, the data_type of cust_address column is set to CUST_ADDRESS_TYP which is an object column of type address_typ.

Really buggers me off as the statement works on varchar type columns but not on this one.

Kind regards,