The most common and most likely answer to this crossword clue is the 8 letter word CANNIEST
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Buddy explains!

The straight part
We know that "Superlatively skilful" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case superlatively skilful = canniest.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 CANNIEST mean?
CANNIEST adjective- Careful, prudent, cautious.
- Knowing, shrewd, astute.
- Frugal, thrifty.
- Pleasant, fair, favorable or agreeable to deal with.
- Gentle, quiet, steady.