The most common and most likely answer to this crossword clue is the 7 letter word IMPAIRS
I've seen this crossword clue in The Daily Telegraph
I
M
P
A
I
R
S
More clues leading to the result IMPAIRS
Buddy explains!
The straight part
We know that "improves? Quite the opposite" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case improves? quite the opposite = impairs.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 IMPAIRS mean?
IMPAIRS verb- To weaken; to affect negatively; to have a diminishing effect on.
- To grow worse; to deteriorate.