Hi Jakep - welcome.
Cryptic clues are usually made uo of two parts, the definition and the clue.
The definition is usually either the first word or two or the last word or two.
In this case, the literal (definition) paert of the clue is either 'editor' or 'expressed disapproval', or maybe just 'disapproval'.
The rest of the clue is the cryptic bit, with a sort of 'code' as to how to confirm that you have the right answer.
One of the most important parts of the clue is the number of letters.
If you ask for help, it's uch easier for us to do that, if you give us as much information as possible, including all punctuation; the letter count and any letters you already have placed.
Others have already given the answer - they're that good, they can work it out without the letter count and so on.
so the definition is 'expressed disapproval' - Objected
the rest is the 'coded' bit. editoris often abbreviated to 'ed'
Purpose is a synonym for object (as in the object of my mission is..)
superior means put the second bit (object) ahead of the second bit 'ed'
so the cryptic bit is object-ed.
Can seem complicated, but the satisfaction in solving a well-constructed clue can be pretty special.
Good luck :)