The woman put on Alien -- film (5)
I believe the answer is:
sheet
'film' is the definition.
(thesaurus)
'the woman put on alien' is the wordplay.
'the woman' becomes 'she' (I've seen this before**).
'put on' is a charade indicator (letters next to each other).
'alien' becomes 'et' (extra terrestrial).
'she'+'et'='SHEET'
(Other definitions for sheet that I've seen before include "Bedcover" , "Piece of linen; ship's rope" , "Bed cover" , "film" , "Piece of paper or bedding" .)