Beer stein (3)
I believe the answer is:
mug
'beer stein' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for mug that I've seen before include "Drinking vessel, by gum" , "A person easily deceived, by gum" , "Large cup without a saucer" , "attack" , "simpleton" .)