Final answer:
In accrual-basis accounting, Clearmore Services should record the service revenue on September 15, the date when the service was actually provided, as revenue is recognized when earned.
Step-by-step explanation:
Using accrual-basis accounting, revenue is recognized when it is earned, regardless of when the payment is actually received. For Clearmore Services, the service was scheduled and provided on September 15. Therefore, according to the principle of revenue recognition under accrual accounting, Clearmore Services should record the service revenue on September 15, the date when the service was actually provided to the customer.