The most common and most likely answer to this crossword clue is the 5 letter word RISHI
I've seen this crossword clue in The Times
R
I
S
H
I
More clues leading to the result RISHI
- Republican is greeting Hindu sage
- Sage in Nagpur — I shine
- Retired teacher greeting Hindu sage
- Gentleman returning, greeting wise man
- Sage European bringing down leader
- Teacher turned up, greeting Hindu sage
- Venerable Asian teacher returned greeting
- Sage from Dublin I dropped completely
- Sage is somewhat boorish individual
- Sage stuffing for burger is hideous
Buddy explains!

The straight part
We know that "Sage" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case sage = rishi.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 RISHI mean?
RISHI noun- A Vedic poet and seer who composed Rigvedic hymns, who alone or with others invokes the deities with poetry of a sacred character.
- (post-Vedic) A Hindu sage or saint occupying the same position in India history as the patriarchs of other countries, constituting a peculiar class of beings in the early mythical system, as distinct from Asuras, Devas and mortal men.