You briefly natter about lawyer (8)
I believe the answer is:
'lawyer' is the definition.
('attorney' can be a synonym of 'lawyer')
'you briefly natter about' is the wordplay.
'briefly' means to remove the last letter.
'about' indicates anagramming the letters.
'you' with its final letter removed is 'yo'.
'yonatter' with letters rearranged gives 'ATTORNEY'.
(Other definitions for attorney that I've seen before include "Any torte (anag.)" , "- jar; - tent; - metal" , "Porter's first employer's occupation" , "An American lawyer or barrister" , "profession" .)