The most common and most likely answer to this crossword clue is the 3 letter word TEE
I've seen this crossword clue in The Times
T
E
E
More clues leading to the result TEE
- Supporter on course initially tackling English exam
- Peg, youngster endlessly
- One in eighteen?
- Sort of shirt, one of a set of eighteen?
- Golf supporter into orienteering
- Driver's aid is what this begins with
- What one might push firmly in before driving?
- Support is there from time to time
- . . . . one giving support
- Quaint little wife coming out to give support
Buddy explains!

The straight part
We know that "One in eighteen?" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case one in eighteen? = tee.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 TEE mean?
TEE noun- The name of the Latin-script letter T.
- Something shaped like the letter T.
- (clothing) T-shirt.
- To draw; lead.
- To draw away; go; proceed.
- A flat area of ground from which players hit their first shots on a golf hole.
- A usually wooden or plastic peg from which a ball is hit.
- The target area of a curling rink
- The mark at which players aim in quoits.
- To place a ball on a tee
- A finial resembling an umbrella, crowning a dagoba in Indochinese countries.