Peaceful ring road runs into cathedral city (7)
I believe the answer is:
orderly
'peaceful' is the definition.
('orderly' can be similar in meaning to 'peaceful')
'ring road runs into cathedral city' is the wordplay.
'ring' becomes 'o'.
'road' becomes 'rd' (abbreviation).
'runs' becomes 'r' (cricket abbreviation).
'into' indicates putting letters inside.
'cathedral city' becomes 'ely' (I've seen this before).
'r' put into 'ely' is 'erly'.
'o'+'rd'+'erly'='ORDERLY'
(Other definitions for orderly that I've seen before include "Regular - neat" , "Hospital attendant - neat" , "Hospital attendant; well behaved" , "Neatly arranged; hospital attendant" , "Methodical, like soldier servant" .)