The most common and most likely answer to this crossword clue is the 7 letter word IRKSOME
I've seen this crossword clue in The Guardian
I
R
K
S
O
M
E
More clues leading to the result IRKSOME
- Mobile or mikes for bugging
- Irish in the end slack, not everyone trying
- Trying Kansas, visiting one city
- I find smoker unusually annoying
- One smoker dreadfully annoying
- Trying one end of cigar — smoke’s blown
- It’s annoying when church defaced roughly?
- Annoying one in front of king and son in capital city
- Annoying smirk one heartlessly contrived
- I find reformed smoker irritating
Buddy explains!

The straight part
We know that "irritating" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case irritating = irksome.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 IRKSOME mean?
IRKSOME adjective- Marked by irritation or annoyance; disagreeable; troublesome by reason of long continuance or repetition