Diplomatic mission of a head of government in a state of elation (8)
I believe the answer is:
legation
'diplomatic mission' is the definition.
(legation is a kind of diplomatic mission)
'head of government in a state of elation' is the wordplay.
I cannot quite understand how this works, but
'government' could be 'g' (abbreviation for government) and 'g' is located in the answer.
an anagram of 'elation' is 'leation' which is present in the remaining letters.
This accounts for all the letters.
This may be the basis of the clue (or it may be nonsense).
'of a' is the link.
Can you help me to learn more?
(Other definitions for legation that I've seen before include "Diplomatic minister and staff, and their residence" , "Embassy" , "A long tie (anag.)" , "Diplomatic group or mission" , "Official residence of diplomat and staff" .)