The most common and most likely answer to this crossword clue is the 4 letter word THIS
I've seen this crossword clue in The Times
T
H
I
S
More clues leading to the result THIS
- The present, or part of ancient history
- not that tears help its suffering at first
- One particular man's on time
- Smash hit's a near thing
- Pronoun featuring in short history
- One particular therapy primarily for a man
- Crossword hard one Eliot admits
- What I’ve got here contributes to ancient history
- Hard one to stop 28 across producing puzzle?
- What ultimately welcomes the caller?
Buddy explains!

The straight part
We know that "One particular" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case one particular = this.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 THIS mean?
THIS noun- Something being indicated that is here; one of these.
- Referring to the current context in a programming environment in C-like languages.
- To the degree or extent indicated.
- The thing, item, etc. being indicated.
- Indicates the speaker's strong approval or agreement with the previous material.