The most common and most likely answer to this crossword clue is the 6 letter word WICKED
I've seen this crossword clue in Financial Times
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More clues leading to the result WICKED
Buddy explains!
The straight part
We know that "Super/nasty" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case super/nasty = wicked.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 WICKED mean?
WICKED noun- People who are wicked.
- Evil or mischievous by nature.
- Excellent; awesome; masterful.
- Very, extremely.
- To convey or draw off (liquid) by capillary action.
- (of a liquid) To traverse (i.e. be conveyed by capillary action) through a wick or other porous material, as water through a sponge. Usually followed by through.
- To strike (a stone) obliquely; to strike (a stationary stone) just enough that the played stone changes direction.
- Having a wick.
- Active; brisk.
- (Alternative form of) wick (Etymology 3 Adjective), as applying to inanimate objects only.
- Infested with maggots.