The most common and most likely answer to this crossword clue is the 7 letter word UNLOOSE
I've seen this crossword clue in The Guardian
U
N
L
O
O
S
E
More clues leading to the result UNLOOSE
Buddy explains!

The straight part
We know that "Free" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case free = unloose.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 UNLOOSE mean?
UNLOOSE verb- To free (someone or something) from a constraint.
- To undo or loosen something that fastens, holds, entangles, or interlocks.