Affecting the whole body (8)
I believe the answer is:
systemic
'affecting the whole body' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for systemic that I've seen before include "Relating to a complex whole" , "Relating to the whole organism" , "City mess (anag)" , "Affecting a body, institution, etc as a whole" , "insecticide" .)