The most common and most likely answer to this crossword clue is the 5 letter word VARNA
V
A
R
N
A
More clues leading to the result VARNA
Buddy explains!

The straight part
We know that "Hindu caste" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case hindu caste = varna.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 VARNA mean?
VARNA noun- Any of the four original castes in Hinduism, or the system of such castes