The most common and most likely answer to this crossword clue is the 6 letter word BEHELD
I've seen this crossword clue in Financial Times
B
E
H
E
L
D
More clues leading to the result BEHELD
- Draw saw
- Suffer detention, as witnessed
- Furniture cut by man with large saw
- Seen to experience the effect of custody?
- Saw, only to become a prisoner
- Saw having ends of blade maintained
- Saw six-footer introducing husband and lord
- Saw the fellow left between the sheets?
- Experience confinement, kept under observation
- Saw be arrested
Buddy explains!

The straight part
We know that "Seen" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case seen = beheld.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 BEHELD mean?
BEHELD verb- To see or look at, esp. appreciatively; to descry, look upon.
- To look.
- To contemplate.