The most common and most likely answer to this crossword clue is the 7 letter word NETTLES
N
E
T
T
L
E
S
More clues leading to the result NETTLES
Buddy explains!

The straight part
We know that "irritates" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case irritates = nettles.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 NETTLES mean?
NETTLES noun- Any plant whose foliage is covered with stinging, mildly poisonous hairs, causing an instant rash.
- Certain plants that have spines or prickles:
- Certain non-stinging plants, mostly in the family Lamiaceae, that resemble the species of Urtica:
- Loosely, anything which causes a similarly stinging rash, such as a jellyfish or sea nettle.
- Of the nettle plant and similar physical causes, to sting, causing a rash in someone.
- To pique, irritate, vex or provoke.