One in church opposing drink (7)
I believe the answer is:
chianti
'drink' is the definition.
(Chianti is an example)
'one in church opposing' is the wordplay.
'one' becomes 'i' (Roman numeral).
'in' indicates putting letters inside.
'church' becomes 'ch' (common abbreviation).
'opposing' becomes 'anti' (prefix meaning 'opposing').
'ch'+'anti'='chanti'
'i' placed into 'chanti' is 'CHIANTI'.
(Other definitions for chianti that I've seen before include "Tuscan red wine" , "Chain it to popular Italian wine" , "I can hit for popular Italian wine" , "Wine produced in Tuscany" , "Dry red Italian wine" .)