Clue: Sight protector in the extreme north, and present in the south-east, certainly (8)
Answer: SNOWEYES
Explanation: Definition: Sight protector in the extreme north
**NOW** ("present") *in* **SE** (south-east) + **YES** ("certainly") 
*Snoweyes were a device, made from whale ivory or driftwood, used by Inuits to prevent snow blindness, a kind of primitive snow goggle.