The most common and most likely answer to this crossword clue is the 3 plus 3 letter word ICE AXE
I've seen this crossword clue in Independent
I
C
E
A
X
E
More clues leading to the result ICE AXE
- Diamond cut accessory for alpinist
- One article carried by climbers primarily?
- Reserve short test to go over mountaineering equipment
- Climber’s aid caught by current after originally falling in river
- Hit peak with this cool guitar?
- One gets stuck in, reaching a peak
- Cool chopper that could help to get one up a mountain
Buddy explains!

The straight part
We know that "mountaineering /equipment" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case mountaineering /equipment = ice axe.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.