The most common and most likely answer to this crossword clue is the 5 letter word RIDER
I've seen this crossword clue in The Guardian
R
I
D
E
R
More clues leading to the result RIDER
- Amendment, one being carried
- Haggard traveller?
- Surprise attacker has lost a horseman
- Traveller is author with American accent, speaking?
- Attacker expressing a further requirement
- Plunderer striking a traveller
- Speculator in stocks overlooking a further clause
- Robber, not a Dick Turpin type?
- Haggard equestrian?
- Possible equestrian’s addition to contract
Buddy explains!

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 RIDER mean?
RIDER noun- One who rides, often on a horse or a motorcycle.
- A provision annexed to a bill under the consideration of a legislature, having little connection with the subject matter of the bill.
- (by extension) Something extra or burdensome that is imposed.
- An amendment or addition to an entertainer's performance contract, often covering a performer's equipment or food, drinks, and general comfort requirements.
- An additional benefit attached to an insurance contract.
- A small, sliding piece of aluminium on a chemical balance, used to determine small weights.
- An agent who goes out with samples of goods to obtain orders; a commercial traveller.
- One who breaks in or manages a horse.
- The first Lenormand card, also known as either the horseman or the cavalier.
- A problem of extra difficulty added to another on an examination paper.
- An old Dutch gold coin with the figure of a man on horseback stamped upon it.
- Rock material in a vein of ore, dividing it.
- An interior rib occasionally fixed in a ship's hold, reaching from the keelson to the beams of the lower deck, to strengthen the frame.
- The second tier of casks in a vessel's hold.
- A small forked weight which straddles the beam of a balance, along which it can be moved in the manner of the weight on a steelyard.
- A robber.
- A piece, such as the rook or bishop, which moves any distance in one direction, as long as no other piece is in the way.