The most common and most likely answer to this crossword clue is the 10 letter word NON-PERSON
I've seen this crossword clue in The Guardian
N
O
N
-
P
E
R
S
O
N
More clues leading to the result NON-PERSON
Buddy explains!
The straight part
We know that "Someone who is ignored/object" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case someone who is ignored/object = non-person.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.