The most common and most likely answer to this crossword clue is the 5 letter word OMBRE
I've seen this crossword clue in The Guardian
O
M
B
R
E
More clues leading to the result OMBRE
- Old card game found in tomb recently
- Card game that was dull? Not to begin with
- Terrible boredom without party game
- Old game medic slices Danish bread
- Ring doctor about card game
- Game played in sombreros
- Man in Spain loses hard game
- Cockney house entertaining bridge card game
- Game over with vacant mob about
- Card game is serious with trumps finally spent
Buddy explains!

The straight part
We know that "game" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case game = ombre.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 OMBRE mean?
OMBRE noun- A large Mediterranean food fish Umbrina cirrosa
- (colors) A gradual blending of one color hue to another, usually moving tints and shades from light to dark.