What is the definition of a credit in accounting?

The correct option is the first one.

In accounting, a credit is an entry made on the right-hand side of a T-account. It typically increases liabilities, equity, and revenue accounts, and decreases asset and expense accounts. When a sum is received, it often involves a credit to a revenue or liability account.

• An entry recording a sum received, listed on the right-hand side or column of an account - This accurately describes a credit. For example, when a business receives cash for services, cash (an asset) is debited, and service revenue (an equity account) is credited. The credit represents the revenue earned from the sum received.

The final answer is $\boxed{\text{An entry recording a sum received, listed on the right-hand side or column of an account}}$