Some film enemy carrying old weapon around (7)
I believe the answer is:
footage
'some film' is the definition.
(footage is a kind of film)
'enemy carrying old weapon around' is the wordplay.
'enemy' becomes 'foe' (I've seen this before).
'carrying' means one lot of letters goes inside another.
'old' becomes 'o' (common abbreviation eg in OE for Old English).
'weapon' becomes 'gat' (gat is a kind of weapon**).
'around' shows that the letters should be reversed in order.
'gat' in reverse letter order is 'tag'.
'o'+'tag'='otag'
'foe' enclosing 'otag' is 'FOOTAGE'.
(Other definitions for footage that I've seen before include "amount of film" , "Piece of filmed material" , "Film that has been shot" , "Length of film" , "quantity shot" .)