The most common and most likely answer to this crossword clue is the 7 letter word SKYWARD
I've seen this crossword clue in The Guardian
S
K
Y
W
A
R
D
More clues leading to the result SKYWARD
Buddy explains!

The straight part
We know that "up" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case up = skyward.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 SKYWARD mean?
SKYWARD adjective- Pointing or facing at or moving toward the sky.
- At or toward the sky.