Out of control city mess affecting an entire body (8)
I believe the answer is:
systemic
'affecting an entire body' is the definition.
(affecting the entire system)
'out of control city mess' is the wordplay.
'out of control' is an anagram indicator.
'city'+'mess'='citymess'
'citymess' anagrammed gives 'SYSTEMIC'.
(Other definitions for systemic that I've seen before include "City mess (anag)" , "My sect is concerned with affecting the whole body" , "insecticide" , "Relating to a complex whole" , "Relating to the whole organism" .)