The most common and most likely answer to this crossword clue is the 4 letter word FROG
I've seen this crossword clue in The Times
F
R
O
G
More clues leading to the result FROG
- Mist surrounds river and pond creature
- Mist surrounding river amphibian
- Defensive blunder by father leaves one hopping!
- Bow adjuster changed for good
- Fastening for jumper
- Mist envelopes rare creature
- . King sunk in gloom – he’ll probably croak
- Animal, bag finally put on back
- Princess’s partner for playing golf
- Jumper Roger needed in misty conditions
Buddy explains!

The straight part
We know that "one hopping" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case one hopping = frog.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 FROG mean?
FROG noun- A small tailless amphibian of the order Anura that typically hops.
- The part of a violin bow (or that of other similar string instruments such as the viola, cello and contrabass) located at the end held by the player, to which the horsehair is attached.
- Road. Shorter, more common form of frog and toad.
- The depression in the upper face of a pressed or handmade clay brick.
- An organ on the bottom of a horse’s hoof that assists in the circulation of blood.
- The part of a railway switch or turnout where the running-rails cross (from the resemblance to the frog in a horse’s hoof).
- To hunt or trap frogs.
- To use a pronged plater to transfer (cells) to another plate.
- To spatchcock (a chicken).
- A French person.
- A French-speaking person from Quebec.
- A leather or fabric loop used to attach a sword or bayonet, or its scabbard, to a waist or shoulder belt.
- An ornate fastener for clothing consisting of an oblong button (covered with netted thread), toggle, or knot, that fits through a loop.
- To ornament or fasten a coat, etc. with frogs.
- To unravel part of (a knitted garment) while knitting it in order to correct a mistake.