There is an requirement to get the DDL for Oracle fusion custom tables is it possible to achieve??
I don't know about working through Fusion itself. If you have a client that can connect to the database you can get the DDL with dbms_metadata:
select dbms_metadata.get_ddl ( 'TABLE', '<table_name>', user );
If you're using SQLcl/SQL Developer you can use the DDL command:
ddl <table_name>