Am turning against wine (5)
I believe the answer is:
macon
'wine' is the definition.
(macon is a kind of wine)
'am turning against' is the wordplay.
'turning' says the letters should be written in reverse.
'against' becomes 'con' (I've seen this before).
'am' back-to-front is 'ma'.
'ma'+'con'='MACON'
(Other definitions for macon that I've seen before include "Wandering (knight)" , "French wine district" , "Dry white Burgundy wine" , "red" , "A heavy Burgundy" .)