A masthead vocal about lacking standards (6)
I believe the answer is:
amoral
'lacking standards' is the definition.
(I've seen this in another clue)
'a masthead vocal' is the wordplay.
'masthead' becomes 'm' (head letter of 'mast').
'vocal' becomes 'oral' (I've seen this in another clue).
'a'+'m'+'oral'='AMORAL'
'about' is the link.
(Other definitions for amoral that I've seen before include "Unprincipled" , "Lacking any ethical sense" , "Lacking principles" , "outrageous!" , "Without ethics" .)