The most common and most likely answer to this crossword clue is the 13 letter word UNAPPRECIATED
I've seen this crossword clue in The Times
U
N
A
P
P
R
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A
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More clues leading to the result UNAPPRECIATED
Buddy explains!

The straight part
We know that "respected" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case respected = unappreciated.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 UNAPPRECIATED mean?
UNAPPRECIATED adjective- Not deemed to have any value, valueless, worthless
- (of an investment) Not having risen in value