Lower a large cocktail (5)
I believe the answer is:
glare
'lower' is the definition.
(thesaurus)
'a large cocktail' is the wordplay.
'cocktail' indicates an anagram.
'large' anagrammed gives 'GLARE'.
(Other definitions for glare that I've seen before include "fierce look" , "Angry look" , "Stare fiercely - 5 down (anag)" , "Scowl angrily" , "Shine intensely" .)