I sing about one Italian drink (7)
I believe the answer is:
chianti
'italian drink' is the definition.
(I've seen this in another clue)
'i sing about one' is the wordplay.
'sing' becomes 'chant' (chanting is a kind of singing).
'about' indicates putting letters inside.
'one' becomes 'I' (Roman numeral).
'i' placed inside 'chant' is 'chiant'.
'chiant'+'i'='CHIANTI'
(Other definitions for chianti that I've seen before include "I can hit (anag) - alcoholic drink" , "Tuscan red wine" , "I can hit for popular Italian wine" , "Italian offering" , "Dry red Italian wine" .)