The most common and most likely answer to this crossword clue is the 6 letter word LOOMED
I've seen this crossword clue in The Times
L
O
O
M
E
D
Buddy explains!

The straight part
We know that "appeared" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case appeared = loomed.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 LOOMED mean?
LOOMED verb- To appear indistinctly, eg. when seen on the horizon or through the murk.
- To appear in an exaggerated or threatening form; to be imminent.
- To rise and to be eminent; to be elevated or ennobled, in a moral sense.