contribute to the already existing literature
This means your first step should be to find 10 articles all about gossip at the work place.
Before you come up with an idea for your thesis, you need to look at what others have done. When you write a little review of 5 or 10 articles, you definitely will start to get ideas about what questions are being left unanswered.
Just imagine how much easier this will be after you have reviewed some articles. You should read an article and write a para, read another and write another.
When you have reviewed several, you will begin to see a theme emerge. Whatever truth is uncovered in your readings, make that your focus!! It is kind of like a trick to write a great paper easily. With paragraphs about any 5 or 10 articles , some unique theme will naturally emerge.
Another good approach would be to focus on a particular kind of company/organization. You can also outline some HRM interventions that have been used to mitigate the consequences of gossip. With this topic, I would just write about whatever topic emerges in the sources (i.e. articles) I found.