Depends on your aircraft and company policy. If your company policy allows you to continue you can just keep it straight, keep current landing flap on a 320 and land. On a 737 you need to go to Flap 15 for single-engine landing due to drag from 30/40 Flap. Some companies take the view that it's best to get it on the ground without delay. You usually don't know what caused the failure (fuel problems??). Others want you to go-around enter the hold and sort it all out for a single-engine approach because they're afaid you might miss something important in the rush to get it on the ground immediately. Both views have some validity in my opinion.