The most common and most likely answer to this crossword clue is the 5 letter word BIKER
I've seen this crossword clue in The Times
B
I
K
E
R
More clues leading to the result BIKER
- Old US president protected by British motorcyclist
- Dispute, but not about gang member?
- One reportedly peddling German ale laced with potassium
- Rocker, AC/DC, at the edge of the pavement, almost?
- Road user’s dispute: “Speed of light disallowed!”
- Old President in Brazil, leathery sort?
- Fight in which Charlie lost to a rider
Buddy explains!

The straight part
We know that "motorcyclist" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case motorcyclist = biker.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 BIKER mean?
BIKER noun- A person whose lifestyle is centered on motorcycles, sometimes a member of a motorcycle club.
- Cyclist