Short, round friend of Dorothy (4)
I believe the answer is:
toto
'friend of dorothy' is the definition.
(Dorothy's pet dog in The Wizard of Oz)
'short round' is the wordplay.
'short' becomes 'tot' (both can mean a small alcoholic drink).
'round' becomes 'o' (round can mean a round object).
'tot'+'o'='TOTO'
(Other definitions for toto that I've seen before include "Dorothy's dog in The Wizard of Oz" , "[FRIEND OF DOROTHY]" , "member of the 5d band" , "Famous film dog" .)