Explanation:

- Try hard to do or achieve something: This means making a strong effort or attempt.

- Option 1, Endanger: This means putting someone or something in a risky or dangerous situation, not related to trying hard.

- Option 2, Hardworking: Describes someone who puts in a lot of effort and perseverance, but it's more about being diligent over time rather than a specific attempt to achieve something.

- Option 3, Endeavour: This word perfectly matches the group of words, as it means to make an earnest attempt to accomplish something.

- Option 4, Indent: Typically refers to starting a line of text a bit inward from the margin or creating a formal requisition, and doesn't relate to making an effort.