The most common and most likely answer to this crossword clue is the 5 letter word GAMER
G
A
M
E
R
More clues leading to the result GAMER
- Leg twisted on person playing
- Perhaps Guitar Hero fan offering a bit of Young Americans
- Player in school having bit of hesitation
- Some losing American player
- Grouse, perhaps beginning to rant with more spirit
- More enthusiastic ‘Fortnite’ player??
- Player walking with difficulty by end of tour
- One plays start of Metal Gear excitedly
- Player representing America putting lots off
- Less cowardly RPG enthusiast
Buddy explains!

The straight part
We know that "One contesting" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case one contesting = gamer.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 GAMER mean?
GAMER noun- A person who plays any kind of game.
- A person whose hobby is video games.
- A person who games the system.
- (obsolete) A gambler
- Willing to participate.
- (of an animal) That shows a tendency to continue to fight against another animal, despite being wounded, often severely.
- Persistent, especially in senses similar to the above.
- Injured, lame (of a limb).