The most common and most likely answer to this crossword clue is the 6 letter word REFITS
I've seen this crossword clue in The Guardian
R
E
F
I
T
S
More clues leading to the result REFITS
Buddy explains!

The straight part
We know that "Makes ready for use again" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case makes ready for use again = refits.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 REFITS mean?
REFITS noun- The process of having something fitted again, repaired or restored.