Fatal weakness (8,4)

I think it could be either:

Which length description are you looking for?:

8,4

achilles heel

'fatal weakness' is the definition.
(I've seen this before)

This is the entire clue.

(Other definitions for achilles heel that I've seen before include "Weak spot for attack" , "Vulnerable part" , "vulnerability" , "A chink in the armour" , "Small but fatal weakness" .)

I've seen this clue in The Telegraph, The Independent and The Times.

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.