This is NOT implemented yet in OSRS, but in RS3.
Since we already can have more than 1 clue scroll of each type (I myself got around 80 elites and 70 hard clues), It would make clue hunting a bit easier if the clue scrolls get stacked in the inventory (instead of an inventory full of clues). I commonly have to check each clue back if it was an easy, medium, hard or elite one, while a stack of these clues would be a bit easier to take with you. It not only safes space, but it also saves ordering the inventory for all the clues that get carried with you.
After completing a clue, the number of carried amount of clues will decrease with 1 and the casket gets in the inventory :) . I have made an example of it below (sorry if my photoshop is bad, I still use paint for it, but you get the idea !)
Let me know what you think! :)
PS: The maximum limit in RS3 is 25 stackable clues.