A Spaniard is a Greek (6)
I believe the answer is:
adonis
'a greek' is the definition.
(I've seen this before)
'a spaniard is' is the wordplay.
'spaniard' becomes 'don' (term for a Spanish gentleman).
'a'+'don'+'is'='ADONIS'
(Other definitions for adonis that I've seen before include "Extremely attractive young man from Greek mythology" , "A very handsome ancient Greek" , "Beautiful young man" , "Handsome fellow" , "male looker" .)