The most common and most likely answer to this crossword clue is the 8 letter word TOEHOLDS
I've seen this crossword clue in The Daily Telegraph
T
O
E
H
O
L
D
S
Buddy explains!

The straight part
We know that "climbers’ requirements" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case climbers’ requirements = toeholds.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 TOEHOLDS mean?
TOEHOLDS noun- A foothold small enough to support just the toe.
- (by extension) Any small advantage which allows one to make significant progress; a slight footing or foothold.
- A hold in which the aggressor bends back the opponent's foot.