The most common and most likely answer to this crossword clue is the 9 letter word WELL-NIGH
I've seen this crossword clue in The Guardian
W
E
L
L
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N
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G
H
More clues leading to the result WELL-NIGH
Buddy explains!

The straight part
We know that "almost" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case almost = well-nigh.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 WELL-NIGH mean?
WELL-NIGH adverb- Almost, nearly.