The most common and most likely answer to this crossword clue is the 8 letter word RATTLING
R
A
T
T
L
I
N
G
More clues leading to the result RATTLING
Buddy explains!

The straight part
We know that "Quick and energetic/extraordinarily good" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case quick and energetic/extraordinarily good = rattling.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 RATTLING mean?
RATTLING verb- To create a rattling sound by shaking or striking.
- To scare, startle, unsettle, or unnerve.
- To make a rattling noise; to make noise by or from shaking.
- To assail, annoy, or stun with a ratting noise.
- To scold; to rail at.
- To drive or ride briskly, so as to make a clattering.
- To make a clatter with one's voice; to talk rapidly and idly; often with on or away.
- Rattle (a sound made by loose objects shaking or vibrating against one another)
- Lively, quick (speech, pace).
- (intensifier) good, fine.
- The rope or similar material used to make cross-ropes on a ship.
- Any of the cross ropes between the shrouds, which form a net like ropework, allowing sailors to climb up towards the top of the mast.