Screen opening of movie on demand (4)
I believe the answer is:
mask
'screen' is the definition.
(thesaurus)
'opening of movie on demand' is the wordplay.
'opening of' suggests taking the first letters.
'on' is a charade indicator (letters next to each other).
'demand' becomes 'ask' ('ask' can be a synonym of 'demand'**).
The initial letter of 'movie' is 'm'.
'm'+'ask'='MASK'
(Other definitions for mask that I've seen before include "Face-covering" , "False face" , "Cover for the face" , "Visor; disguise" , "Camouflage" .)