Jealousy about nothing is representative (5)
I believe the answer is:
envoy
'is representative' is the definition.
(I've seen this in another clue)
'jealousy about nothing' is the wordplay.
'jealousy' becomes 'envy' (jealousy is an envious feeling).
'about' means one lot of letters goes inside another.
'nothing' becomes 'o' (O resembles 0).
'envy' going around 'o' is 'ENVOY'.
(Other definitions for envoy that I've seen before include "Diplomat" , "Diplomatic representative" , "Legate" , "Ambassador" , "final words in writing" .)