A short final, unfortunately (4)
I believe the answer is:
alas
'unfortunately' is the definition.
(I've seen this before)
'a short final' is the wordplay.
'short' means to remove the last letter.
'final' becomes 'last' ('last' can be a synonym of 'final').
'last' with its last letter removed is 'las'.
'a'+'las'='ALAS'
(Other definitions for alas that I've seen before include "Oh dear!" , "-- and alack!" , "Interjection of sorrow" , "Sad expression" , "More's the pity" .)