The most common and most likely answer to this crossword clue is the 4 plus 3 letter word YEAR DOT
I've seen this crossword clue in Independent
Y
E
A
R
D
O
T
More clues leading to the result YEAR DOT
- Ready to change a long time ago
- Beginning? Ready to get knocked out?
- Ready to burst ages ago
- Indeed, right before origins of dawn of time?
- In the beginning ready to run
- Desire endless pepper, as far as anyone can remember
- Spooner’s cherished vessel said to be square one
- Ready-to-cook for a very long time
- Ready to change at the earliest time
- . Instill road discipline, right at the beginning
Buddy explains!

The straight part
We know that "In the beginning" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case in the beginning = year dot.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.