Show mode off (4)
I believe the answer is:
demo
'show' is the definition.
(I know that demo is a more specific form of show)
'mode off' is the wordplay.
'off' is an anagram indicator.
'mode' with letters rearranged gives 'DEMO'.
(Other definitions for demo that I've seen before include "Tape sent to recording studio" , "March (abbr)" , "Protest march (sl.)" , "Protest (abbr)" , "exhibit" .)