The most common and most likely answer to this crossword clue is the 5 letter word FLASH
F
L
A
S
H
More clues leading to the result FLASH
- Ostentatious female with leather?
- Maybe Gordon put family jewels on display?
- Loud note gets quiet in an instant
- Briefly show yourself to be ostentatious
- Instant force with whip
- Gaudy loud tie
- Twinkling beam
- Ostentatious moment
- Speedily kept unharmed by cold in marsh, poor Flora embraces quiet
- Brandish loud whip
Buddy explains!

The straight part
We know that "Instant" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case instant = flash.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 FLASH mean?
FLASH noun- A device that produces a short flash of light to help illuminate a scene, mostly for night-time or indoors photography.
- A sudden, short, temporary burst of light.
- A very short amount of time.
- A flashlight; an electric torch.
- A sudden and brilliant burst, as of genius or wit.
- Material left around the edge of a moulded part at the parting line of the mould.
- (Cockney) The strips of bright cloth or buttons worn around the collars of market traders.
- A pattern where each prop is thrown and caught only once.
- A language, created by a minority to maintain cultural identity, that cannot be understood by the ruling class.
- A preparation of capsicum, burnt sugar, etc., for colouring liquor to make it look stronger.
- A form of military insignia.
- Any of various lycaenid butterflies of the genera Artipe, Deudorix and Rapala.
- A tattoo flash.
- The sudden sensation of being "high" after taking a recreational drug.
- A newsflash.
- To cause to shine briefly or intermittently.
- To blink; to shine or illuminate intermittently.
- To be visible briefly.
- To make visible briefly.
- To briefly, and often unintentionally, expose one's naked body or underwear, or part of it, in public. (Contrast streak.)
- To show or expose an "inappropriate" part of the body to someone for humorous reasons or as an act of contempt.
- To break forth like a sudden flood of light; to show a momentary brilliance.
- To flaunt; to display in a showy manner.
- To communicate quickly.
- To move, or cause to move, suddenly.
- To telephone a person, only allowing the phone to ring once, in order to request a call back.
- (of liquid) To evaporate suddenly. (See flash evaporation.)
- To climb (a route) successfully on the first attempt.
- To write to the memory of (an updatable component such as a BIOS chip or games cartridge).
- (glassmaking) To cover with a thin layer, as objects of glass with glass of a different colour.
- (glassmaking) To expand (blown glass) into a disc.
- To send by some startling or sudden means.
- To burst out into violence.
- To perform a flash.
- To release the pressure from a pressurized vessel.
- To trick up in a showy manner.
- To strike and throw up large bodies of water from the surface; to splash.
- Expensive-looking and demanding attention; stylish; showy.
- (of a person) Having plenty of ready money.
- (of a person) Liable to show off expensive possessions or money.
- Occurring very rapidly, almost instantaneously.
- Relating to thieves and vagabonds.
- A pool.
- A reservoir and sluiceway beside a navigable stream, just above a shoal, so that the stream may pour in water as boats pass, and thus bear them over the shoal.