The most common and most likely answer to this crossword clue is the 10 letter word OCCASIONAL
I've seen this crossword clue in The Daily Telegraph
O
C
C
A
S
I
O
N
A
L
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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 OCCASIONAL mean?
OCCASIONAL noun- A person who does something only occasionally.
- Occurring or appearing irregularly from time to time, but not often.
- Created for a specific occasion.
- Intended for use as the occasion requires.
- Acting in the indicated role from time to time.