SQL> connect sys
Enter password: ***
Connected.
SQL> grant create procedure to mag;

Grant succeeded.

SQL> connect mag
Enter password: ***
Connected.
SQL> set serveroutput on
SQL>  create or replace procedure dynamic_test is
  2   string varchar2(200);
  3   begin
  4   string := 'create or replace procedure dyn is begin dbms_output.put_line(''asdf''); end;';
  5   execute immediate string;
  6   end;
  7  /

Procedure created.

SQL> exec dynamic_test;

PL/SQL procedure successfully completed.

SQL> exec dyn
asdf

PL/SQL procedure successfully completed.

SQL>