Unfinished theatrical production shot (4)
I believe the answer is:
dram
'shot' is the definition.
(of whisky say)
'unfinished theatrical production' is the wordplay.
'unfinished' means to remove the last letter.
'theatrical production' becomes 'drama' (a dramatic work).
'drama' with its last letter removed is 'DRAM'.
(Other definitions for dram that I've seen before include "Apothecary's weight, 60 grains" , "Short" , "little weight" , "Wee drop of whisky?" , "shot" .)