The most common and most likely answer to this crossword clue is the 5 plus 4 letter word READY MADE
I've seen this crossword clue in Financial Times
R
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A
D
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More clues leading to the result READY MADE
Buddy explains!
The straight part
We know that "available immediately" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case available immediately = ready made.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 READY MADE mean?
READY MADE noun- A ready-made object.
- Pre-existing or made previously and suitable for use without (further) preparation or modification; comparable with regard to the amount of preparation required.
- Made in advance to a standard specification.
- Made or prepared in advance and used regularly or habitually without original thought.