The most common and most likely answer to this crossword clue is the 6 letter word TUPELO
T
U
P
E
L
O
Buddy explains!
The straight part
We know that "Tree" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case tree = tupelo.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 TUPELO mean?
TUPELO noun- Any of several trees of the genus Nyssa which grow in swampy regions on the eastern, southern and midwestern United States.