False clone claiming ambassador's rank (7)
I believe the answer is:
echelon
'rank' is the definition.
(I've seen this before)
'false clone claiming ambassador's' is the wordplay.
'false' is an anagram indicator.
'claiming' is an insertion indicator.
'ambassador' becomes 'he' (His or Her Excellency).
'clone' anagrammed gives 'eclon'.
'eclon' placed around 'he' is 'ECHELON'.
(Other definitions for echelon that I've seen before include "Level or rank in a group" , "Body of troops arranged in a line" , "Military stepped formation" , "Level or rank of authority, upper or lower" , "Leech on (anag.)" .)