The most common and most likely answer to this crossword clue is the 8 letter word TOASTING
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More clues leading to the result TOASTING
Buddy explains!

The straight part
We know that "Wishing all the best" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case wishing all the best = toasting.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 TOASTING mean?
TOASTING verb- To lightly cook by browning via direct exposure to a fire or other heat source.
- To grill, lightly cook by browning specifically under a grill or in a toaster
- To engage in a salutation and/or accompanying raising of glasses while drinking alcohol in honor of someone or something.
- To warm thoroughly.
- To perform extemporaneous narrative poem or rap.
- The action of making a toast (celebratory call to drink).
- The heating of oak panels used to make wine barrels.
- The process by which something, such as bread, is toasted.