Famous clown having a beverage (5)
I believe the answer is:
cocoa
'beverage' is the definition.
(cocoa is a kind of beverage)
'famous clown having a' is the wordplay.
'famous clown' becomes 'coco' (Coco the Clown, 20th-century clown).
'having' says to put letters next to each other.
'coco'+'a'='COCOA'
(Other definitions for cocoa that I've seen before include "Reddish brown" , "Chocolate ingredient" , "drink from beans" , "Warming bedtime drink" , "Bedtime drink made from powder" .)