The phrase "had up a tree" is commonly used to describe a situation where someone finds themselves in a tricky or challenging situation. There are several synonyms that can be used to replace this phrase, depending on the context in which it is being used. Some of these alternatives include "stuck up a tree" which suggests a feeling of being trapped or unable to move, "climbed up a tree" which implies that the individual intentionally went up the tree, and "perched on a tree" which depicts a person sitting or standing on a tree limb. Similarly, "treed" or "up a gum tree" can also be used to denote a feeling of being in trouble or difficulty. Ultimately, the choice of synonym depends on the intended meaning of the phrase in the given context.