Endlessly seek advice from diplomat (6)
I believe the answer is:
consul
'diplomat' is the definition.
(consul is a kind of diplomat)
'endlessly seek advice from' is the wordplay.
'endlessly' means to remove the last letter.
'seek advice from' becomes 'consult' (I've seen this before).
'consult' with its final letter taken away is 'CONSUL'.
(Other definitions for consul that I've seen before include "Ambassador" , "Diplomat abroad" , "Magistrate in ancient Rome or modern diplomat" , "Old Roman official" , "Roman chief magistrate" .)