The most common and most likely answer to this crossword clue is the 6 letter word SIERRA
I've seen this crossword clue in Financial Times
S
I
E
R
R
A
More clues leading to the result SIERRA
- Mountainous country - I make a mistake entering it
- Climbing is to go wrong on a mountain range
- Range is rare, however
- Travelling is rare in a mountain range
- Chain letter read out on radio
- Unlimited Asian sin within range
- Mountain range in South Africa? I’m mistaken
- Chain of supermarkets in Egypt runs regular adverts at first
- Ford car range
- Model gets disheartened over artist’s range
Buddy explains!

The straight part
We know that "Mountain range" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case mountain range = sierra.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 SIERRA mean?
SIERRA noun- A rugged range of mountains.
- The letter S in the ICAO spelling alphabet.
- A scombroid fish.
- A relatively low-quality grade of Spanish saffron.