Sweetheart gets unsettled about ending in feature film (4,5)
I believe the answer is:
beau geste
'film' is the definition.
(I've seen this before)
'sweetheart gets unsettled about ending in feature' is the wordplay.
'sweetheart' becomes 'beau' (beau can mean a sweetheart or lover).
'unsettled' indicates an anagram.
'about' means one lot of letters goes inside another.
'ending in' indicates one should take the final letters.
The last letter of 'feature' is 'e'.
'gets' with letters rearranged gives 'gest'.
'beau' going within 'gest' is 'beaugest'.
'beaugest'+'e'='BEAU GESTE'
(Other definitions for beau geste that I've seen before include "Noble act; French foreign legion novel" , "Gracious act (Fr.); film" , "magnanimous act" , "Wren's work" .)