The most common and most likely answer to this crossword clue is the 3 plus 9 plus 10 letter word THE SHAWSHANK REDEMPTION
I've seen this crossword clue in The Guardian
T
H
E
S
H
A
W
S
H
A
N
K
R
E
D
E
M
P
T
I
O
N
Buddy explains!
The straight part
We know that "Film" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case film = the shawshank redemption.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.