The most common and most likely answer to this crossword clue is the 7 letter word DWINDLE
I've seen this crossword clue in The Times
D
W
I
N
D
L
E
More clues leading to the result DWINDLE
- Decrease in expected wind level
- Die down? Some wretched wind lessens
- Snake left in den after cutting tail off
- Arid wind leads palms to shrink
- End wild chaos and peter out
- Cold wind led hedges to shrink
- Degenerate son leaves fleece for daughter
- Flag raised; wind lessened to an extent
- Weaken in bad wind
- In cold wind leaves get smaller
Buddy explains!

The straight part
We know that "Decrease" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case decrease = dwindle.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 DWINDLE mean?
DWINDLE verb- To decrease, shrink, diminish, reduce in size or intensity.
- To fall away in quality; degenerate, sink.
- To lessen; to bring low.
- To break up or disperse.