A patient of depression is getting chlorpromazine, but his auditory hallucination is not controlled. The next drug given is -

The patient is taking chlorpromazine, i.e., the patient is taking treatment for schizophrenia. Auditory hallucinations are not controlled, therefore he is having resistant schizophrenia for which clozapine is the drug of choice. Don't get confused with depression (as written in question) because depression may occur in schizophrenia. If It would have been depression patient would have been taking antidepressants not antipsychotics. So, this patient is suffering from schizophrenia with associated depression.