Clinical = طِبّی

Psychologist = ماہر نفسیات

clinical psychology: Branch of psychology concerned with the diagnosis and treatment of mental disorders. Clinical psychologists evaluate patients through interviews, observation, and psychological tests, and they apply current research findings and methodologies in making diagnoses and assigning treatments. They may provide psychotherapy but cannot prescribe medications. Most practictioners work in hospitals or clinics or in private practice, often in tandem with psychiatrists and social workers, treating mentally or physically disabled patients, prison inmates, drug and alcohol abusers, and geriatric patients, among others

Most of the above translations are correct but none is being used practically in the society rather its transliteration is much common amongst the concerned circles. If the word is psychologist alone then its translation is much common but clinical psychologist is comparatively new term, so its translation is not that common yet.