The most common and most likely answer to this crossword clue is the 5 letter word LUNGE
I've seen this crossword clue in Financial Times
L
U
N
G
E
More clues leading to the result LUNGE
- Organ adds energy for fast movement
- Move suddenly east after a breather
- Train on line to advance suddenly
- Attack enemy leader after a breather
- Sudden movement in bar — nothing spilt!
- Sudden attack, somewhat uncivil, ungentlemanly
- Move forward quickly, having energy after breather
- Forward movement mostly not relying on gills?
- Take a breather before final decisive strike
- Movement of part of body needing energy
Buddy explains!

The straight part
We know that "strike" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case strike = lunge.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 LUNGE mean?
LUNGE noun- A sudden forward movement, especially with a sword.
- A long rope or flat web line, more commonly referred to as a lunge line, approximately 20–30 feet long, attached to the bridle, lungeing cavesson, or halter of a horse and used to control the animal while lungeing.
- An exercise performed by stepping forward one leg while kneeling with the other leg, then returning to a standing position.
- A fish, the namaycush.
- To (cause to make) a sudden forward movement (present participle: lunging).
- To longe or work a horse in a circle around a handler (present participle: lunging or lungeing).