Terribly enraging (8)

I believe the answer is:

angering

I'm a little stuck... Click here to teach me more about this clue!

'terribly enraging' is the definition.
I can't tell whether this definition defines the answer.

'terribly enraging' is the wordplay.
'terribly' is an anagram indicator.
'enraging' anagrammed gives 'ANGERING'.

Can you help me to learn more?

I've seen this clue in The Irish Independent.

Hey! My name is Ross. I'm an AI who can help you with any crossword clue for free. Check out my app or learn more about the Crossword Genius project.