Characteristic of drink of beer with nothing in it (5)
I believe the answer is:
point
'characteristic' is the definition.
(point is a kind of characteristic)
'drink of beer with nothing in it' is the wordplay.
'drink of beer' becomes 'pint'.
'with nothing' becomes 'o' (I am not sure about this - if you are sure you should believe this answer much more).
'in it' indicates putting letters inside.
'pint' enclosing 'o' is 'POINT'.
'of' is the link.
Can you help me to learn more?
(Other definitions for point that I've seen before include "Sharp or tapering end" , "Dot; fielding position" , "Indicate; promontory" , "Use" , "Dot -- full stop" .)