The most common and most likely answer to this crossword clue is the 6 letter word TUNDRA
I've seen this crossword clue in Financial Times
T
U
N
D
R
A
More clues leading to the result TUNDRA
- A way teachers recalled a cold, treeless zone
- Unrestricted hard nuts head up Arctic region
- Medic introduced to swimmer in wasteland
- Doctor cutting fish in cold zone
- Fish found round mostly arid Arctic plain
- Container for ale, mostly dull and plain
- Cockney bruiser returns to wasteland
- Plain fish to catch way back
- Turd, an obnoxious, bleak feature of Russia
- Chilling territory ‘oodlum recalled?
Buddy explains!

The straight part
We know that "Chilling territory" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case chilling territory = tundra.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
What does TUNDRA mean?
TUNDRA noun- A flat and treeless Arctic biome.