Below is an example to print CLOB data using PL/SQL dynamic content in Oracle Apex.

Create a region as PL/SQL dynamic content and add the following code in the PL/SQL code section:

declare
v_clob clob;
n_amt INTEGER := 4000;
n_pos INTEGER := 1;
v_buf VARCHAR2(4000);
begin

Select yourClobColumn into v_clob
  from yourTable where col1 = :px_item;

loop
begin
 dbms_lob.read(v_clob, n_amt, n_pos, v_buf);
 n_pos := n_pos + n_amt;
 htp.p(v_buf); 
 exception
 when no_data_found then
   exit;
end;
end loop;
END;