The most common and most likely answer to this crossword clue is the 6 letter word ENIGMA
I've seen this crossword clue in Independent
E
N
I
G
M
A
More clues leading to the result ENIGMA
- Puzzle in game to be worked out
- Poser trounced in game
- Imagine not starting cryptic puzzle
- WWII device: a piece of ordnance used around about capital of Germany
- Puzzle in game needs to be worked out
- Unhappily imagine being short of one puzzle
- Wartime machine with some variations?
- Mystery when head of gold found in a hole pulled up
- Riddle of English graduate imbibing drink from east?
- New game in for puzzle
Buddy explains!

The straight part
We know that "puzzle" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case puzzle = enigma.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 ENIGMA mean?
ENIGMA noun- Something or someone puzzling, mysterious or inexplicable.
- A riddle, or a difficult problem.