Certain evergreen

FIR

This tree’s needles are soft and flat, often used for Christmas decorations and known for its straight, towering growth in northern forests.

"Certain evergreen" is a straightforward definition clue pointing to a type of tree that stays green year-round. The answer is "FIR," which fits because firs are a common evergreen conifer. There’s no hidden wordplay here—it’s a direct clue where the answer matches the description exactly. Think of Christmas trees, and you’ve got the right idea.