The most common and most likely answer to this crossword clue is the 2 plus 3 letter word AB OVO
A
B
O
V
O
Buddy explains!
The straight part
We know that "from the word go" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case from the word go = ab ovo.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.