Film celebrities fighting inside (4,4)
I believe the answer is:
star wars
'film' is the definition.
(I've seen this before)
'celebrities fighting inside' is the wordplay.
'celebrities' becomes 'stars' (I've seen this in other clues).
'fighting' becomes 'war'.
'inside' is an insertion indicator.
'stars' going around 'war' is 'STAR WARS'.
(Other definitions for star wars that I've seen before include "Movie" , "George Lucas's cult sci-fi film" , "Space fiction film - SDI" , "Strategic Defense Initiative (US) - sci-fi film" , "Cult film - Reagan initiative" .)