spool file.csv
select
'"'col1||'","'||
to_char(amount_field,'9999.99')||'"'
from table1

SQL> select * from t1;

AMOUNT_FIELD
------------
        1234
     1234.99

SQL> spool /tmp/file.csv
SQL> select to_char(amount_field, '9999.99') from t1;

TO_CHAR(
--------
 1234.00
 1234.99

SQL> spool off
SQL> !cat /tmp/file.csv
SQL> select to_char(amount_field, '9999.99') from t1;

TO_CHAR(
--------
 1234.00
 1234.99

SQL> spool off

SQL> desc test;
Name Type         Nullable Default Comments 
---- ------------ -------- ------- -------- 
COL1 VARCHAR2(12) Y                         
COL2 DATE         Y                         

SQL> desc test;
Name         Type         Nullable Default Comments 
------------ ------------ -------- ------- -------- 
COL1         VARCHAR2(12) Y                         
AMOUNT_FIELD NUMBER       Y                        

SQL> spool C:\temp\file.csv
Started spooling to C:\file.csv

SQL> set head off;
SQL> select
'"'||col1||'","'||
trim(to_char(amount_field,'9999.99'))||'"'
from test
"Hoe","23.00"
"Joe","123.99"

SQL> spool off
Stopped spooling to C:\temp\file.csv 

Hoe	         123
Joe	         123.99