Note: Please note that you would require to run catmeta.sql for the creation of the views related to DBMS_METADATA.
This Script is available under $ORACLE_HOME/rdbms/admin directory.


select dbms_metadata.get_ddl('TABLE','IDX3_TAB','SAPSR3') from dual;

To get the create table definition without the storage clause you could do 
as follows:

EXECUTE DBMS_METADATA.SET_TRANSFORM_PARAM(DBMS_METADATA.SESSION_TRANSFORM,'STORAGE',false);