No need to worry. Saturn in the 10th house of your solar return points to a work year that is serious, heavy in tone and maybe a bit stressful. The fact that you've just started a new job with real responsibility is already a sign of that.
Saturn is known as the "greater malefic", but in truth he is a teacher. He pushes you hard, but he raises you. Life works the same way; the lasting lessons come from the hard periods.
Things at work may not flow easily this year. Whether you do the job properly may be questioned, strict attention to working hours will be expected, and there may be stress, heavy workload, pressure, even mobbing. If you meet all this in Saturn's own language, with maturity, discipline, order and a cool head, the same Saturn gives you permanence and solidity. He puts you on firmer ground than where you started and secures your position.
Still, one planet alone doesn't say much. The full solar return chart may show a very different picture, and making a firm judgment from this little information would be a mistake.