In the middle of a film, director gets stuck in (6)
I believe the answer is:
amidst
'in the middle of' is the definition.
(I've seen this before)
'a film director gets stuck in' is the wordplay.
'film' becomes 'mist' (to film over is to mist or fog over).
'director' becomes 'd' (abbreviation eg in film reviews).
'gets stuck in' means one lot of letters goes inside another.
'mist' enclosing 'd' is 'midst'.
'a'+'midst'='AMIDST'
(Other definitions for amidst that I've seen before include "In the thick of" , "During; within" , "Surrounded by" , "Beset" , "It's mad (anag.)" .)