The most common and most likely answer to this crossword clue is the 3 letter word NAG
I've seen this crossword clue in The Times
N
A
G
More clues leading to the result NAG
Buddy explains!

The straight part
We know that "Old Arab maybe" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case old arab maybe = nag.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 NAG mean?
NAG noun- A small horse; a pony.
- An old useless horse.
- A paramour.
- Someone or something that nags.
- A repeated complaint or reminder.
- A persistent, bothersome thought or worry
- To continuously remind or complain to (someone) in an annoying way, often about insignificant or unnecessary matters.
- To bother with persistent thoughts or memories.
- To bother or disturb persistently in any way.