The most common and most likely answer to this crossword clue is the 6 letter word ASCEND
I've seen this crossword clue in Financial Times
A
S
C
E
N
D
More clues leading to the result ASCEND
- Get promoted in a post broadcasting
- When cold finish move up
- Charlie filling a post to gain promotion
- Commercial in which scene cut to scale
- Zoom for instance to finish around end of pandemic
- Heard donkey tail is to be raised
- A second C to terminate scale
- Poster, including cropped picture, to go up
- Climb in Alsace regularly before death
- Regularly sick at finish, after a climb
Buddy explains!

The straight part
We know that "th/e up" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case th/e up = ascend.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 ASCEND mean?
ASCEND verb- To move upward, to fly, to soar.
- To slope in an upward direction.
- To go up.
- To succeed.
- To rise; to become higher, more noble, etc.
- To trace, search or go backwards temporally (e.g., through records, genealogies, routes, etc.).
- To become higher in pitch.