To say the fourth season is a whirlwind for Clay is an understatement. After all the trauma he's been through, Clay starts dissociating. He's seeing a shrink regularly but continues to go off the rails. He vandalises the school, sets the dean's car on fire, and torments his friends, all while dissociating.
The school shooting drill lands Clay in the hospital's mental ward after he has a breakdown and starts waving a gun around, but he breaks out and goes to his therapist for help. He starts to get better and be supportive for his friends, and they choose him to speak at graduation.
Clay also breaks off his relationship with Ani, knowing he's not in a place for a relationship. His friendship with Justin grows closer and closer, with Justin even referring to Clay as his brother. Clay gets accepted to Brown University and ends the season on his way to Nevada to help Tony get settled in at school.