I just accepted an edit I actually wanted to improve, because I misclicked. Now I can not cancel my review, and I can not edit the question myself because of the pending edit.
Is there anything you can do?
As you remarked, you cannot edit the post right now, and you cannot go back on the review either. But as a user with full editing privileges you can edit the post after the pending suggested edit is approve or rejected.
Thus, you could keep an eye on the question, for example you could favorite it, and then check back on it. Usually suggested edits are handled with not too much delay, thus this seems rather feasible.
Depending on the nature of the edit you could also leave a comment explaining the situation and briefly explaining what would need to be improved or fixed. Maybe somebody else will pick up on it then.