The most common and most likely answer to this crossword clue is the 10 letter word DOWNDRAFTS
I've seen this crossword clue in The Times
D
O
W
N
D
R
A
F
T
S
Buddy explains!
The straight part
We know that "in US winds up? On the contrary" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case in us winds up? on the contrary = downdrafts.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 DOWNDRAFTS mean?
DOWNDRAFTS noun- A strong, downward air current; an air pocket or air hole