The most common and most likely answer to this crossword clue is the 5 letter word RAGER
I've seen this crossword clue in The Guardian
R
A
G
E
R
More clues leading to the result RAGER
Buddy explains!
The straight part
We know that "one very cross" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case one very cross = rager.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 RAGER mean?
RAGER noun- One who rages.
- A party, particularly a large, wild party (social event).
- A raging erection; a massive erection of the penis.