To become or cause s.o. to be apprehensive [N-]; to worry or be apprehensive about s.t. or s.o. [0, -an, ka--an].
Don't be afraid of that horse. He isn't going to do anything.
I'm concerned about him because he might be defeated.
I'm not going to cause you to be apprehensive lest you not be able to climb that tree.
The thing I'm worried about with him is that he might have capsized.