Dumb show (4)
I believe the answer is:
mime
'dumb show' is the definition.
(I know that dumb show can be written as mime)
This is all the clue.
(Other definitions for mime that I've seen before include "Act without speaking" , "Wagnerian role?" , "Acting without speaking" , "Pretend to sing" , "Express something with actions and gestures alone" .)