Overweight supporter ending in disaster (7)

I believe the answer is:

fatally

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

'overweight supporter ending in disaster' is the definition.
I can't judge whether this definition defines the answer.

'overweight supporter ending' is the wordplay.
'overweight' becomes 'fat' (similar in meaning).
'supporter' becomes 'ally' (ally can mean a supporter or friend).
'ending' means one lot of letters go next to another.
'fat'+'ally'='FATALLY'

Can you help me to learn more?

(Other definitions for fatally that I've seen before include "producing disastrous result" , "So as to cause death" , "Might one be wounded thus" , "with no hope of revival" , "in decisive manner" .)

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.