at the top of the tree —(also: at the top of the heap)
1. as high as possible in one’s career or profession:
- You’re asking us to believe that a man right at the top of his particular tree, is going to commit forgery.
2. of the highest rank within a group of items:
- You may be selling products on behalf of another company, or you might be the company at the top of the tree…
up a tree—
1. (coll.) in trouble or difficulty (also: up a gumtree):
- The news that no hotel accommodations were obtainable left me rather up a tree.
2. (sl.) alcohol intoxicated:
- Only two glasses of booze and he was up a tree for sure.
Note:
a) The expression does not correlate in meaning with the phrase up the pole—(sl.)
1. (UK) confused or muddled:
- The Pope told Galileo that he was up the pole for pretending the world was round.
2. (Irish) pregnant:
- “Is she up the pole?”“Better ask Seymour that.”
b) The expression is not antonymous in meaning to the phrase out of one’s tree—(sl.) crazy; lacking common sense:
- I do believe that Bill was out of his tree when he made this decision.