Ancient Italian trained centaurs (8)
I believe the answer is:
etruscan
'ancient italian' is the definition.
(I've seen this before)
'trained centaurs' is the wordplay.
'trained' is an anagram indicator (to train can mean to grow something into a shape).
'centaurs' anagrammed gives 'ETRUSCAN'.
(Other definitions for etruscan that I've seen before include "Of an ancient people of central Italy" , "Ancient Italian language" , "Of ancient Tuscany" , "Early Roman" , "Centaurs (anag) -- native of an ancient state of central Italy" .)