The most common and most likely answer to this crossword clue is the 8 letter word MOUNTAIN
I've seen this crossword clue in The Sunday Telegraph
M
O
U
N
T
A
I
N
More clues leading to the result MOUNTAIN
- Horse, near Aintree's front three, fell maybe
- Eg Ben’s horse, popular around area
- Horse active in elevated region
- Significant relief when donkey, say, gets a home
- Horse that’s wild in a rocky place
- Part of chain found on such a bike
- Horse excellent, hitting new peak
- Horse with excellent name — Ben, maybe?
- Horse at home eating a huge quantity
- Huge quantity swirling in a tum, no?
Buddy explains!

The straight part
We know that "high position" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case high position = mountain.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 MOUNTAIN mean?
MOUNTAIN noun- An elevation of land of considerable dimensions rising more or less abruptly, forming a conspicuous figure in the landscape, usually having a small extent of surface at its summit.
- Something very large in size or quantity; a huge amount; a great heap.
- Of, belonging to, relating to, or found on a mountain; like a mountain in size; (of living things) growing or living on a mountain.
- A difficult task or challenge.
- A woman's large breast.
- The twenty-first Lenormand card.
- Wine made from grapes that grow on a mountain.