Because he wants to help his friend Victor Frankenstein, and also wanted to study oriental languages.
Victor's reaction to Clerval's death was one of devastation and guilt, similar to his reaction when the creature was brought to life. Both events stirred strong emotions of regret and responsibility within Victor, as he felt directly responsible for the outcomes. The deaths of both Clerval and the creature's creation led Victor to confront the consequences of his actions and the havoc they wreaked on those he cared about.