See about one small amount of liquid cocktail (6)
I believe the answer is:
gimlet
'cocktail' is the definition.
(gimlet is a kind of cocktail)
'see about one small amount of liquid' is the wordplay.
'see' becomes 'get' (I've seen this before).
'about' is an insertion indicator.
'one' becomes 'I' (Roman numeral).
'small amount of liquid' becomes 'ml' (short for mililitre).
'i'+'ml'='iml'
'get' enclosing 'iml' is 'GIMLET'.
(Other definitions for gimlet that I've seen before include "Gin and lime juice cocktail - boring tool" , "One pierces" , "Small tool for boring holes" , "Tool for boring holes and a cocktail" , "Wood-boring tool" .)