The most common and most likely answer to this crossword clue is the 8 letter word SOLSTICE
I've seen this crossword clue in The Times
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More clues leading to the result SOLSTICE
- Fish holding short stick in biannual event
- Note slippery patch on road: that is expected in December
- Time of year to get sun on street and evidence of freezing
- Fish holding short rod in biannual event
- Criticism mainly fuels exclusive star’s most ‘out there’ position
- Turning point in star’s career is close perhaps? About time
- Lost cities heartlessly demolished, a turning point
- Closet is turned out for date in June, perhaps
- Time off after costliest revamping — a turning-point for 1 Across
- It’s close-set at the beginning of summer
Buddy explains!

The straight part
We know that "biannual event" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case biannual event = solstice.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 SOLSTICE mean?
SOLSTICE noun- One of the two points in the ecliptic at which the sun is furthest from the celestial equator. This corresponds to one of two days in the year when the day is either longest or shortest.