Sentence:  In theory , compulsive behavior is a way of diminishing anxiety , and one might expect a negative association except for the possibility that for many children the obsessive-compulsive <WSD>defenses</WSD> are not sufficient to quell the amount of anxiety they suffer . 
Meaning of the word marked with <WSD> tags:  (psychiatry) an unconscious process that tries to reduce the anxiety associated with instinctive desires