The option that can be used as a one-word substitute for the given group of words "An omission of duty" is "Delinquency."

Let's provide a detailed explanation for each option:

1. Surrender: Surrender refers to the act of yielding or giving up control or possession, typically in a situation of conflict or opposition. It does not directly relate to the concept of an omission of duty.

2. Delinquency: Delinquency refers to the failure to fulfill a duty or obligation, particularly when it involves legal or moral responsibilities. It implies a neglect or omission of duty, often associated with wrongdoing or non-compliance.

3. Deliberation: Deliberation refers to the process of carefully considering or discussing a matter before making a decision. It involves thoughtful and thorough examination, rather than an omission of duty.

4. Delineation: Delineation refers to the act of describing or depicting something with precision or detail. It involves outlining or portraying a subject, but it does not specifically convey the idea of an omission of duty.

Therefore, in the given context, the correct option that can be used as a one-word substitute for "An omission of duty" is "Delinquency," as it specifically refers to the failure or neglect in fulfilling a duty or responsibility.