Ah yes, I have one like this, though mine is a bit older (7.5). There's a sensory-seeking element to it, I find - we've had dolls clothes cut up, hair cut off, holes cut in bedding etc etc. It's not deliberate naughtiness or attention-seeking, cos she generally tries to keep it hidden, it's more a kind of compulsive testing out and re-enacting of whatever the current idea is. As well as cutting we've had writing/drawing on walls, smearing stuff on walls/furniture/surfaces, pickign things apart, standing on objects that are clearly not strong or stable enough to take her weight etc etc. We've also had multiple trips to A&E (fracture clinic/wound glue, beads up nose/vagina/ear) resulting from her overwhelming urge to find out 'what will happen if I do this?'
It's a combination of sensory seeking, poor verbal memory (she is notably not good at retaining things that have been said to her, despite a fiendishly good memory for things she's seen or read), poor sense of cause and effect and high impulsivity. She is bright and can concentrate, so it's not a learning disability or ADHD, though it probably is immaturity. Telling her off doesn't work, and can even be counter-productive cos she quite likes the drama of being shouted at.
What has helped? Not much, tbh. Getting her to acknowledge that she has sensory urges helps a bit, as does deliberately giving her outlets for it give her old catalogues to cut up, worn-out socks, whatever. I bought a large tub of theraputty which she knows she can ask for when she comes back from school, and I have tried to increase the opportunities for her to do other types of messy play, much as you would for a younger child cheap shaving foam, jelly, wet spaghetti, making potions etc etc. If you can get her to acknowledge to herself that she has these impulses, then that's one step closer to getting her to channel them in an appropriate direction. Very calm explanations can also help, esp if you break down the thought processes into very small steps: "what can you do if you want to cut things? Is it a good idea to cut clothes? Why not? What will happen if you cut your T-shirt up? Do you like it when I get angry with you? What could you do instead? What can you do to help yourself remember that? What will you do next time you want to cut something? That's right, you'll remember that I have a bag of things you're allowed to cut, so you'll come and ask me for it, and that way you know you won't get into trouble for it".
Sympathies, though, it is very wearing, especially when you're dealing with a child who ought to be far too old for that kind of randomness. It will get better, but it may take a while. In the meantime keep all the scissors locked up.