Your employer is responsible for your safety at work. This includes taking action to prevent violent, abusive and threatening behaviour from customers, clients, fellow workers and the general public. And if you are attacked, you can expect support from your employer. If you don't feel safe at work you should raise this with your safety rep or line manager.
At the same time, you should think carefully about the risks you face at work. Diana Lamplugh, who founded The Suzy Lamplugh Trust after her daughter was abducted in 1986, says: "The only way to enable someone to be safe is for them to decide to be safe for themselves. To ask questions of themselves, such as 'What would I do if…?' or 'If this should happen, then what would I do?' Practise the 'If this… then what?' scenarios until they become second nature. Knowing your way round gives confidence, changes behaviour and makes you less likely to be an easy target."
Violence and abuse at work may be unpredictable, but it is preventable.