Anglians occasionally express colloquial opposition (4)
I believe the answer is:
agin
'express colloquial opposition' is the definition.
I know nothing about this answer so I cannot judge whether it can be defined by this definition.
'anglians occasionally' is the wordplay.
'occasionally' means one should take alternating letters (letters taken at regular intervals or occasions).
The alternate letters of 'anglians' are 'AGIN'.
Can you help me to learn more?
(Other definitions for agin that I've seen before include "Not a fan of" , "Opposed to local" , "Dialect form of against" , "Hostile to" , "Not in favour of" .)