The most common and most likely answer to this crossword clue is the 8 letter word KNOW-ALL
K
N
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W
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A
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Buddy explains!
The straight part
We know that "Smart alec" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case smart alec = know-all.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 KNOW-ALL mean?
KNOW-ALL noun- Someone who obnoxiously claims to be knowledgeable on a subject.