The most common and most likely answer to this crossword clue is the 8 letter word NETTLING
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More clues leading to the result NETTLING
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 = nettling.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 NETTLING mean?
NETTLING verb- Of the nettle plant and similar physical causes, to sting, causing a rash in someone.
- To pique, irritate, vex or provoke.
- (ropemaking) A process, resembling splicing, by which two ropes are joined so as to form one rope.
- The process of tying together the ends of yarns in pairs, to prevent tangling.
- The process of stinging somebody with nettles.