Resistance to disease (8)
I believe the answer is:
immunity
'resistance to disease' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for immunity that I've seen before include "legal protection?" , "I'm involved in mutiny, with special exemption (8)" , "Safety from prosecution, disease etc" , "Inability to catch a cold" , "may be diplomatic" .)