The most common and most likely answer to this crossword clue is the 7 letter word UNCLOSE
U
N
C
L
O
S
E
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The straight part
We know that "Open/not stuffy" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case open/not stuffy = unclose.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 UNCLOSE mean?
UNCLOSE verb- To open; to unclench.