How can I use comma-seperated-list in pl-sql if block

I have a plsql procedure.

 procedure get_data
    (P_CONCEPT_ID NUMBER_TYPE)
    is 
      v_concept_list varchar2(2000);

begin

select LISTAGG(column_value, ',') WITHIN GROUP (ORDER BY column_value) into v_concept_list from table(P_CONCEPT_ID);

cursor v_cur_concepts is
        select distinct concept_id, max(main_concept_id) .......;


for rec in v_cur_concepts loop
     ........
       if rec.concept_id in (**v_concept_list**) then

                    dbms_output.put_line(rec.concept_id);
       end if;
 end loop;

after I convert procedure in parameter to a string list, how can I use this in if clause? It maked me really tired :(

Thanks..