Ambassador, cultured and exuberant (6)
I believe the answer is:
hearty
'exuberant' is the definition.
(I've seen this before)
'ambassador cultured' is the wordplay.
'ambassador' becomes 'he' (His or Her Excellency).
'cultured' becomes 'arty' (I've seen this before).
'he'+'arty'='HEARTY'
'and' acts as a link.
(Other definitions for hearty that I've seen before include "Vigorously healthy" , "Vigorous and in good spirits, being earthy" , "full of enthusiasm" , "Jovial fellow" , "Without reservation, satisfying" .)