The most common and most likely answer to this crossword clue is the 6 plus 4 letter word STANDS FAST
I've seen this crossword clue in The Guardian
S
T
A
N
D
S
F
A
S
T
Buddy explains!
The straight part
We know that "rises quickly/rises quickly/doesn’t budge/doesn’t budge" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case rises quickly/rises quickly/doesn’t budge/doesn’t budge = stands fast.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.