Channel Islands serve up the last word in film (6)
I believe the answer is:
cinema
'film' is the definition.
('cinema' can be a synonym of 'film')
'channel islands serve up the last word' is the wordplay.
'channel islands' becomes 'ci'.
'serve up' shows that the letters should be reversed in order.
'the last word' becomes 'amen' (I've seen this before).
'amen' in reverse letter order is 'nema'.
'ci'+'nema'='CINEMA'
'in' is the link.
(Other definitions for cinema that I've seen before include "Movie theatre" , "multiplex, perhaps" , "Picture house" , "Filmdom" , "(Building for) the movies" .)