The bit most likely to give way is the skew ankle; it collapses (3,7,4)
I believe the answer is:
the weakest link
'the bit most likely to give way' is the definition.
I don't know anything about this answer so I cannot tell whether it can be defined by this definition.
'the skew ankle it collapses' is the wordplay.
'collapses' is an anagram indicator.
'skew'+'ankle'+'it'='skewankleit'
'skewankleit' anagrammed gives 'weakestlink'.
'the'+'weakestlink'='THE WEAKEST LINK'
'is' acts as a link.
Can you help me to learn more?
(Other definitions for the weakest link that I've seen before include "contestants humiliated) in this" , "game on TV" .)