The most common and most likely answer to this crossword clue is the 5 letter word UNLET
I've seen this crossword clue in Financial Times
U
N
L
E
T
More clues leading to the result UNLET
Buddy explains!

The straight part
We know that "Available to rent" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case available to rent = unlet.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 UNLET mean?
UNLET adjective- (of property) Not let (not in temporary possession in return for rent)