Diplomat to seek advice shortly (6)
I believe the answer is:
consul
'diplomat' is the definition.
(I know that consul is a type of diplomat)
'seek advice shortly' is the wordplay.
'seek advice' becomes 'consult' (I've seen this in another clue).
'shortly' means to remove the last letter.
'consult' with its final letter taken away is 'CONSUL'.
'to' is the link.
(Other definitions for consul that I've seen before include "Magistrate in ancient Rome or modern diplomat" , "Diplomat abroad" , "Roman chief magistrate" , "National representative in a foreign city" , "The diplomat deals with commercial matters" .)