Diplomatic staffer to fix date at last (7)
I believe the answer is:
attache
'diplomatic staffer' is the definition.
(I've seen this in another clue)
'fix date at last' is the wordplay.
'fix' becomes 'attach' (I've seen this before).
'date at last' becomes 'e' (I can't justify this - if you can you should give a lot more credence to this answer).
'attach'+'e'='ATTACHE'
'to' acts as a link.
Can you help me to learn more?
(Other definitions for attache that I've seen before include "Tea chat (anag.)" , "Small rectangular document case" , "ambassador's assistant" , "Embassy member" , "Embassy worker" .)