This diplomat needs to have dined at his place of work (6)
I believe the answer is:
consul
'this diplomat' is the definition.
(consul is a kind of diplomat)
'to have dined at his place of work' is the wordplay.
I cannot really see how this works, but
'at' could be 'on' (location) and 'on' is found within the answer.
This may be the basis of clue (or it may be nonsense).
'needs' acts as a link.
Can you help me to learn more?
(Other definitions for consul that I've seen before include "Ambassador" , "Official representative of a state living abroad" , "Magistrate in ancient Rome or modern diplomat" , "Diplomat abroad" , "Chief magistrate in ancient Rome" .)