The most common and most likely answer to this crossword clue is the 4 letter word FURY
I've seen this crossword clue in Independent
F
U
R
Y
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The straight part
We know that "anger" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case anger = fury.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 FURY mean?
FURY noun- Extreme anger.
- Strength or violence in action.
- An angry or malignant person.
- A thief.