Shocker in short, also (2,4)
I believe the answer is:
to boot
'also' is the definition.
(I've seen this in another clue)
'shocker in short' is the wordplay.
'shocker' becomes 'boo' (you might say 'boo!' to shock someone).
'in' is an insertion indicator.
'short' becomes 'tot' (both can mean a small alcoholic drink).
'boo' inserted within 'tot' is 'TO BOOT'.
(Other definitions for to boot that I've seen before include "Into the bargain" , "furthermore" , "Where an extra case may be added" , "Kick" , "Besides, in addition - think footwear" .)