You don't want to use CLOB unless its absolutely necessary. Trust me specifying varchar2 is not a waste of space. The only way I would use CLOB is if I had video/pdf...etc files that took up too much space. Stick with Tony's advice.
Dont forget varchar2's only take up the same amount of space as the string you put in. So if you put in a short string say size 10 bytes then the column will take up 10 bytes plus a terminating character. Of course if you put a large string and then update it to a short string there will be wasted space in the row.