Reduced voucher against wine (7)
I believe the answer is:
chianti
'wine' is the definition.
(Chianti is an example)
'reduced voucher against' is the wordplay.
'reduced' means to remove the last letter.
'voucher' becomes 'chit' (I've seen this before).
'against' becomes 'anti' (I've seen this before).
'chit' with its final letter taken off is 'chi'.
'chi'+'anti'='CHIANTI'
(Other definitions for chianti that I've seen before include "European wine" , "Popular dry red wine of Tuscany" , "Italian wine variety" , "Italian wine - mountain range" , "Wine produced in Tuscany" .)