The most common and most likely answer to this crossword clue is the 4 plus 2 plus 3 plus 4 letter word COME TO THE FORE
C
O
M
E
T
O
T
H
E
F
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R
E
Buddy explains!
The straight part
We know that "become visible" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case become visible = come to the fore.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.