The most common and most likely answer to this crossword clue is the 8 letter word BLIGHTER
I've seen this crossword clue in Independent
B
L
I
G
H
T
E
R
More clues leading to the result BLIGHTER
- Wretch born on boat
- Bachelor having lost weight is a villain
- Fellow bachelor, not carrying as much weight
- Bachelor, not so serious a pest
- Wretch born on dock boat
- Beggar is baron, short of a few pounds?
- Beggar born on barge
- Beggar beginning to board barge
- Beggar beginning to barge barge
- Character in pub finally getting dizzier, an irritating guy
Buddy explains!

The straight part
We know that "irritating guy" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case irritating guy = blighter.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 BLIGHTER mean?
BLIGHTER noun- One who blights.
- (often disrespectful) A person, usually male, especially one who behaves in an objectionable or pitiable manner.