The most common and most likely answer to this crossword clue is the 9 letter word CLEVEREST
I've seen this crossword clue in The Daily Telegraph
C
L
E
V
E
R
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S
T
More clues leading to the result CLEVEREST
- Most intelligent tips from climber leaving mountain
- First in college, learner with highest place — being this?
- Brightest climbers initially left mountain
- Extremely cerebral peak of superlative brilliance
- Not even cold at the top, extremely bright
- Very smart to get clip without one person on mountain
- Regularly scale peak, becoming most competent
- Smartest pair of climbers on the world’s highest mountain
- Smartest pair of climbers on highest mountain
Buddy explains!

The straight part
We know that "superlative brilliance" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case superlative brilliance = cleverest.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 CLEVEREST mean?
CLEVEREST adjective- Nimble with hands or body; skillful; adept.
- Resourceful, sometimes to the point of cunning.
- Smart, intelligent, or witty; mentally quick or sharp.
- Showing inventiveness or originality; witty.
- (of an Aboriginal Australian) Possessing magical abilities.
- Fit; suitable; having propriety.
- Well-shaped; handsome.
- Good-natured; obliging.
- Fit and healthy; free from fatigue or illness.