Supports for “floater” and “stinger|” showing unexpected weakness (4,2,4)
I believe the answer is:
feet of clay
'unexpected weakness' is the definition.
(feet of clay can mean a fundamental weakness)
'supports for floater and stinger' is the wordplay.
I cannot quite understand how this works, but
'supports' could be 'feet' (foot is a kind of support) and 'feet' is found within the answer.
This explanation may well be incorrect...
'showing' acts as a link.
(Other definitions for feet of clay that I've seen before include "Fatal flaw in an otherwise admirable character" , "Unexpected flaw in someone revered" , "Character flaws in a person otherwise revered" , "lepidopteran floaters, once?" , "Defect" .)