Shock fine just? (6)
I believe the answer is:
fright
'shock' is the definition.
(I've seen this before)
'fine just?' is the wordplay.
'fine' becomes 'f' (abbreviation).
'just?' becomes 'right' ('right' can be similar in meaning to 'just').
'f'+'right'='FRIGHT'
(Other definitions for fright that I've seen before include "Grotesque" , "Terror" , "A scare or shock" , "Start" , "Shock, intense fear" .)