Large sniper drunk lager (7)
I believe the answer is:
pilsner
'lager' is the definition.
(I've seen this before)
'large sniper drunk' is the wordplay.
'large' becomes 'l'.
'drunk' indicates anagramming the letters.
'l'+'sniper'='lsniper'
'lsniper' with letters rearranged gives 'PILSNER'.
(Other definitions for pilsner that I've seen before include "Czech beer" , "drink" , "Type of lager" , "alcohol" , "Bar tab might include this" .)