The Clue Anxiety condition with repetitive behaviour (abbr.)
The Answer OCD
OCD stands for Obsessive-Compulsive Disorder, which is an anxiety condition. People with OCD often have unwanted thoughts, called obsessions, that lead to repetitive behaviors, known as compulsions. These compulsions are performed to reduce the anxiety caused by the obsessions. The abbreviation "OCD" fits perfectly as the answer to the crossword clue.