The most common and most likely answer to this crossword clue is the 9 letter word DISCERNED
I've seen this crossword clue in The Daily Telegraph
D
I
S
C
E
R
N
E
D
Buddy explains!

The straight part
We know that "Caught sight of" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case caught sight of = discerned.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 DISCERNED mean?
DISCERNED verb- To detect with the senses, especially with the eyes.
- To perceive, recognize, or comprehend with the mind; to descry.
- To distinguish something as being different from something else; to differentiate.
- To perceive differences.