The most common and most likely answer to this crossword clue is the 5 letter word MUGGY
I've seen this crossword clue in Financial Times
M
U
G
G
Y
More clues leading to the result MUGGY
Buddy explains!

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 MUGGY mean?
MUGGY adjective- (Of the weather, air, etc) humid, or hot and humid.
- Wet or mouldy