The most common and most likely answer to this crossword clue is the 10 letter word UNRESERVED
I've seen this crossword clue in The Daily Telegraph
U
N
R
E
S
E
R
V
E
D
More clues leading to the result UNRESERVED
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 = unreserved.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 UNRESERVED mean?
UNRESERVED adjective- (of a person) Not reserved, without reservations.
- Not booked in advance.
- To undo or cancel a reservation.