Some mainstream movie content for magazines (4)
I believe the answer is:
ammo
'content for magazines' is the definition.
The definition and answer can be both man-made objects as well as being singular nouns.
Perhaps there's an association between them I don't understand?
'some mainstream movie' is the wordplay.
'some' indicates a hidden word (some of the parts of the word are used).
'AMMO' is hidden within 'mainstream movie'.
Can you help me to learn more?
(Other definitions for ammo that I've seen before include "round" , "Bullets, shells (colloq.)" , "Bullets (sl.)" , "Bullets and bombs, etc (abbr)" , "Bullets (abbrev.)" .)