The most common and most likely answer to this crossword clue is the 3 letter word MAC
I've seen this crossword clue in Independent
M
A
C
More clues leading to the result MAC
Buddy explains!

The straight part
We know that "(Apple) kit for IT" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case (apple) kit for it = mac.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 MAC mean?
MAC noun- A waterproof long coat made of rubberized cloth.
- By extension, any waterproof coat or raincoat.
- Waterproof rubberized cloth.
- A type of pasta in the form of short tubes; sometimes loosely, pasta in general.
- A fop, a dandy; especially a young man in the 18th century who had travelled in Europe and who dressed and often spoke in an ostentatiously affected Continental manner.