Man suffering with amazing stress to achieve style (9)
I believe the answer is:
smartness
'style' is the definition.
(I've seen this in another clue)
'man suffering with amazing stress' is the wordplay.
I cannot quite understand how this works, but
'man' could be 'mart' and 'mart' is found within the answer.
This may be the basis of the clue (or it may be nonsense).
'to achieve' is the link.
Can you help me to learn more?
(Other definitions for smartness that I've seen before include "Clean and tidy quality" , "characteristic of some cards" , "Elegance" , "Fashionable nature" , "style" .)