The most common and most likely answer to this crossword clue is the 7 letter word HORIZON
I've seen this crossword clue in The Guardian
H
O
R
I
Z
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N
More clues leading to the result HORIZON
Buddy explains!
The straight part
We know that "as far as one can see" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case as far as one can see = horizon.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 HORIZON mean?
HORIZON noun- The visible horizontal line or point (in all directions) that appears to connect the Earth to the sky.
- The range or limit of one's knowledge, experience or interest; a boundary or threshold.
- The range or limit of any dimension in which one exists.
- A specific layer of soil or strata
- A cultural sub-period or level within a more encompassing time period.
- Any level line or surface.
- The point at which a computer chess algorithm stops searching for further moves.