The most common and most likely answer to this crossword clue is the 8 letter word OCCASION
I've seen this crossword clue in The Daily Telegraph
O
C
C
A
S
I
O
N
More clues leading to the result OCCASION
- Event in Illinois accounted for uprising
- Time when half of 12 backed one with a parsimonious rule mostly
- Special day for children’s ending after cocoa is drunk
- Is smeared with cocoa at start of new party
- In company twice as exceptional, it’s a special event
- Need time
- Provoke incident
- Firm retired watchmaker? About time
- Do call
- Bring on, for instance
Buddy explains!

The straight part
We know that "Do/call" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case do/call = occasion.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 OCCASION mean?
OCCASION noun- A favorable opportunity; a convenient or timely chance.
- The time when something happens.
- An occurrence or state of affairs which causes some event or reaction; a motive or reason.
- Something which causes something else; a cause.
- An occurrence or incident.
- A particular happening; an instance or time when something occurred.
- Need; requirement, necessity.
- A special event or function.
- A reason or excuse; a motive; a persuasion.
- To cause; to produce; to induce