Liqueur drunk at a fair (7)
I believe the answer is:
ratafia
'liqueur' is the definition.
(ratafia is a kind of liqueur)
'drunk at a fair' is the wordplay.
'drunk' indicates anagramming the letters.
'at'+'a'+'fair'='atafair'
'atafair' with letters rearranged gives 'RATAFIA'.
(Other definitions for ratafia that I've seen before include "Kind of liqueur" , "Cordial" , "Almond flavouring essence" , "Almond-flavoured biscuit - at a fair (anag)" , "Biscuits" .)