The most common and most likely answer to this crossword clue is the 13 letter word INDETERMINATE
I've seen this crossword clue in The Times
I
N
D
E
T
E
R
M
I
N
A
T
E
More clues leading to the result INDETERMINATE
- Poor internet media of uncertain value
- Deem itinerant drunk to be unsettled
- Unspecified dinner and teatime must be sorted out
- A tender time in Barking is unknown
- One end muddled with another? It’s not known
- Denis, seconds away, failed to stop when uncertain
- Vague tirade with eminent lunatic …
- Uncertain having organised teatime and dinner
- Meatier tinned liquid could be uncertain
- Dinnertime is fixed, and tea flexible, not exactly fixed
Buddy explains!
The straight part
We know that "unknown" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case unknown = indeterminate.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 INDETERMINATE mean?
INDETERMINATE adjective- Not accurately determined or determinable.
- Imprecise or vague.
- (of certain forms of limit) Not definitively or precisely determined, because of the presence of infinity or zero symbols used in any of several improper combinations.
- (of growth) With no genetically defined end, and thus theoretically limitless.
- (of inflorescences) Not topped with some form of terminal bud.
- Intersex.
- Designed to allow the incorporation of future changes whose nature is not yet known.