The most common and most likely answer to this crossword clue is the 7 letter word AGILITY
I've seen this crossword clue in The Guardian
A
G
I
L
I
T
Y
More clues leading to the result AGILITY
- Gaily, it moves, displaying this?
- Delicacy father sacrificed for speed
- Soldier fired into area close to enemy, showing quick-wittedness
- Talent that’s good for British briskness
- Acrobat shows this delicacy without leading duo
- Sprightliness of a soldier burning before end of enmity
- A soldier landed by end of runway demonstrating dexterity
- German supplanting Britain in talent for nimbleness
- A gold plate conducting current with variable physical property
Buddy explains!

The straight part
We know that "speed" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case speed = agility.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 AGILITY mean?
AGILITY noun- The quality of being agile; the power of moving the limbs quickly and easily; quickness of motion
- A faculty of being agile in body, mind, or figuratively.