One attacking home with sci-fi villain? (7)
I believe the answer is:
invader
'one attacking' is the definition.
(an invader attacks a territory)
'home with sci-fi villain?' is the wordplay.
'home' becomes 'in' ('he's home' can mean 'he's in').
'with' is a charade indicator (letters next to each other).
'sci-fi villain?' becomes 'Vader' (Darth Vader from Star Wars).
'in'+'vader'='INVADER'
(Other definitions for invader that I've seen before include "One enters by force to conquer" , "Encroacher" , "Attacker from outside" , "Attacker from abroad" , "One entering by force" .)