Lung affliction covers one piece of beef (1-4)
I believe the answer is:
t-bone
'lung affliction covers one' is the definition.
I know nothing about this answer so I can't judge whether this works.
'piece of beef' is the wordplay.
I cannot really understand how this works, but
'piece' could be 'bone' (bone is a kind of piece) and 'bone' is located in the answer.
A single letter 't' remains which might be clued in a way I don't see.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for t-bone that I've seen before include "Choice piece of loin steak" , "Cut of beef" , "Large cut of steak" , "Type of steak" , "Kind of steak" .)