The most common and most likely answer to this crossword clue is the 7 letter word PASTERN
I've seen this crossword clue in The Times
P
A
S
T
E
R
N
Buddy explains!
The straight part
We know that "part of Arab's leg" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case part of arab's leg = pastern.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 PASTERN mean?
PASTERN noun- The part of a horse's leg between the fetlock joint and the hoof.
- A shackle for horses while pasturing.
- A patten.