The most common and most likely answer to this crossword clue is the 6 letter word HEWING
I've seen this crossword clue in The Daily Telegraph
H
E
W
I
N
G
More clues leading to the result HEWING
Buddy explains!

The straight part
We know that "process to remove trees" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case process to remove trees = hewing.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 HEWING mean?
HEWING verb- To chop away at; to whittle down; to mow down.
- To shape; to form.
- To act according to, to conform to; usually construed with to.
- The act of one who hews or chops.