inserting blob/clob over dblinks
To insert lobs over a database link, your inserts need to be in the form:
INSERT INTO table1@remote_site SELECT * FROM local_table;
http://docs.oracle.com/database/121/ADLOB/adlob_working.htm#ADLOB45148
You can do this by:

Creating a temporary table
Loading your clob data into the temp table
The insert over the DB link with &quot;insert@link .. select&quot;

For example:
create table t (
id int,
x clob
);
create global temporary table gtt (
id int,
x clob
) on commit preserve rows;
declare
l clob;
begin
insert into gtt values ( 1, empty_clob() )
returning x into l;
for i in 1 .. 10 loop
dbms_lob.writeappend(l, 4000, lpad('x', 4000, 'x'));
end loop;
commit;
insert into t@loopback
select * from gtt;
end;
/
select id, length(x) from t;
    ID  LENGTH(X)


     1      40000

(Loopback is a DB link pointing back to the same database)