The most common and most likely answer to this crossword clue is the 7 letter word UNCORKS
I've seen this crossword clue in The Guardian
U
N
C
O
R
K
S
Buddy explains!

The straight part
We know that "Unleashes" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case unleashes = uncorks.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 UNCORKS mean?
UNCORKS verb- To open (a bottle or other container sealed with a cork or stopper) by removing the cork or stopper from.
- To release.