Glaring error primarily confronted by advocates generally (9)
I believe the answer is:
barefaced
'glaring' is the definition.
(both can mean brazen or obvious)
'error primarily confronted by advocates generally' is the wordplay.
'primarily' says to take the initial letters.
'confronted' becomes 'faced' ('face' can be a synonym of 'confront').
'by' means one lot of letters go next to another.
'advocates generally' becomes 'bar' ('the bar' can refer to the legal profession).
The initial letter of 'error' is 'e'.
'e'+'faced'='efaced'
'efaced' put after 'bar' is 'BAREFACED'.
(Other definitions for barefaced that I've seen before include "having just had a close shave" , "Shameless like liar, having shaven visage" , "Unshaven kind of blatant liar" , "Unveiled, perhaps" , "such lies?" .)