There are several ways one can respond to what one is experiencing on the outside. There is a "clean" way that completes and integrates things, and there is a "dirty" way that leaves things incomplete and fragmented.
We could say one only runs into problems externally with stuff one hasn't integrated internally. So the external situation shows you what you haven't dealt with internally. And then one has two possible routes for completing the loop:
1. One can do it the aberrated way of re-internalizing a distorted interpretation of the external phenomenon. I.e. one can store a redundant facsimile with an fragmented, limiting picture of what is going on. Like an traumatic incident, an upset, a fixed idea or whatever. And thereby one builds up incomplete stuff in one's space. That is done by having semantic reactions, and responding to what one thinks, rather than to what is actually happening. It is done by considering oneself to be effect of the environment and reacting to guard oneself against it.
If one has a car accident and one subconsciously stores the elements of it in one's mind, to remember to stay away from them, and as a reminder that one "screwed up" or that one is "unlucky", that is an aberrated internalization.
2. One can internalize it by taking responsibility for it. I.e. one can recognize how the external phenomenon reflects one's internal state of mind. That completes the loop with an integration, a resolution, a completion. The external circumstance would tend to disappear and one is left with an internalized learning from it. This is done by actually noticing what goes on, by realizing what it has to do with you, and by drawing a learning out of it that empowers you.
If one has a car accident and one realizes how one set it up by the way one had been thinking and feeling, and one realizes what lesson there is to learn from the incident, how it is a positive growth experience, then there will be no lingering negative effect. On the contrary.
A worsening spiral would be when one loops around one cycle, from internal to external to internal, but one ends up with a distorted view rather than a completion. Therefore one has to keep looping around, reacting to one's own mis-understandings and reactions.
For example, one sees a red-haired man drive quickly away with a car, looking like a thief. Then a new neighbor with red hair moves in. One labels him a criminal and expects the worst from him. He one day is so kind as to receive a package in the mail for you when you are out. You now know "for sure" that he was trying to rip you off. You grow more and more nervous from living in such an "unsafe" neighborhood, and develop ulcers. Because of that you feel mistreated by the medical system, and you conclude that everybody is trying to do you in. And so forth. That would be an aberrated spiral, making things repeatedly worse by one's own distorted reactions.
Clearing is about getting things really finished so they don't have to be repeated.