Stop admitting a latitude that's commonly accepted (9)
I believe the answer is:
prevalent
'commonly accepted' is the definition.
(prevalent can mean well-established or accepted)
'stop admitting a latitude' is the wordplay.
'stop' becomes 'prevent' (stop can mean to prevent something).
'admitting' means one lot of letters goes inside another (admit can mean to welcome in or accept).
'latitude' becomes 'L' (abbreviation for latitude).
'a'+'l'='al'
'prevent' placed around 'al' is 'PREVALENT'.
'that's' acts as a link.
(Other definitions for prevalent that I've seen before include "powerful" , "general" , "Common" , "Widely accepted" , "Commonplace" .)