Backed the Italian, one wearing kinky green underwear (8)
I believe the answer is:
lingerie
'underwear' is the definition.
(lingerie is a kind of underwear)
'backed the italian one wearing kinky green' is the wordplay.
'backed' says the letters should be written backwards.
'the italian' becomes 'il' (the in Italian).
'one' becomes 'i' (Roman numeral).
'wearing' is an insertion indicator.
'kinky' is an anagram indicator.
'il' backwards is 'li'.
'green' is an anagram of 'ngere'.
'i' put within 'ngere' is 'ngerie'.
'li'+'ngerie'='LINGERIE'
(Other definitions for lingerie that I've seen before include "pants! Could be" , "Slinky undergarments" , "frillies" , "One from W Atlantic island group" , "Women's underwear from France" .)