City mess problem is pervasive (8)
I believe the answer is:
systemic
'pervasive' is the definition.
Both the definition and answer are adjectives. Maybe they are linked in a way I don't understand?
'city mess problem' is the wordplay.
'problem' indicates anagramming the letters.
'city'+'mess'='citymess'
'citymess' is an anagram of 'SYSTEMIC'.
'is' is the link.
Can you help me to learn more?
(Other definitions for systemic that I've seen before include "Relating to the whole organism" , "Affecting a body, institution, etc as a whole" , "insecticide" , "My sect is concerned with affecting the whole body" , "Relating to a complex whole" .)