Infuriates convenience when about to add (7)

I believe the answer is:

maddens

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

'infuriates' is the definition.
The definition and answer can be both to do with human feelings as well as being verbs in their -s form.
Maybe there's a link between them I don't understand?

'convenience when about to add' is the wordplay.
'convenience' becomes 'men's' (men's is a kind of convenience).
'when about' indicates putting letters inside.
'mens' placed around 'add' is 'MADDENS'.

Can you help me to learn more?

I've seen this clue in the Sydney Morning Herald.

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.