Accept no authority from a fatheaded oaf (5)
I believe the answer is:
flout
'accept no authority' is the definition.
I can't tell whether this definition defines the answer.
'a fatheaded oaf' is the wordplay.
'a fatheaded' becomes 'f' (this might be a standard abbreviation which I don't know about).
'oaf' becomes 'lout' (synonyms).
'f'+'lout'='FLOUT'
'from' is the link.
Can you help me to learn more?
(Other definitions for flout that I've seen before include "Disobey openly and scornfully" , "Treat with contempt" , "Ignore (rule)" , "Mock" , "Defy (orders etc)" .)