Has this film finally bombed? Or maybe it's this! (5,3)
I believe the answer is:
smash hit
'maybe it's this' is the definition.
I don't know anything about this answer so I can't tell whether it can be defined by this definition.
'has this film finally bombed?' is the wordplay.
'finally' suggests the final letters.
'bombed?' is an anagram indicator (I've seen 'bombed' mean this).
The last letter of 'film' is 'm'.
'has'+'this'+'m'='hasthism'
'hasthism' anagrammed gives 'SMASH-HIT'.
'or' is the link.
(Other definitions for smash hit that I've seen before include "successful play?" , "big success" , "number one" , "blockbuster" , "Huge success" .)