The Greek word “askeo”

Found just once in the New Testament (Acts 24:16), the Greek verb “askeo” meant “practice, engage in, take pains.”

Paul told Felix he always strove to keep a clean conscience in the sight of both God and men.  Brown (Dictionary of New Testament Theology, 1:495) expressed the thought as:  “‘I also take pains at all times to have a clear conscience.’”