The word "clambered up" indicates an action of climbing or ascending, but there are numerous antonyms that imply descending or moving downwards. Some possible antonyms for "clambered up" may include "descended", "climbed down", "descended rapidly", "slid down", "descended smoothly", "dropped down", "descended slowly", and "lowered oneself down". These antonyms highlight the opposite direction of movement, suggesting a downward motion instead of an upward one. Using these antonyms can add depth and nuance to a piece of writing, helping to create a more vivid and detailed picture of the action taking place.