The most common and most likely answer to this crossword clue is the 6 letter word DINNER
I've seen this crossword clue in The Daily Telegraph
D
I
N
N
E
R
More clues leading to the result DINNER
- The German eats local meal
- Duke having private meal
- Finally fed such a man here?
- Incense driver after smashing plates, etc
- Revolutionary coming back to eat pub grub?
- Dutch leader having exclusive meal
- Someone eating has a double portion of something in meal
- For banquet, hotel rejected wine boxes
- Meal in end cooked close to another
- Meal of diced red onion when old duck’s off
Buddy explains!

The straight part
We know that "Main board meeting of the day?" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case main board meeting of the day? = dinner.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 DINNER mean?
DINNER noun- A midday meal (in a context in which the evening meal is called supper or tea).
- The main meal of the day, often eaten in the evening.
- An evening meal.
- A meal given to an animal.
- A formal meal for many people eaten for a special occasion.
- The food provided or consumed at any such meal.
- To eat a dinner.
- To provide (someone) with a dinner.